Fiber Reinforced Composites in Pediatric Dentistry

Fiber Reinforced Composites in

Pediatric Dentistry Frc in Pediatric Dentistry

Dr. Sunita Agarwalla, et al.

Medical and Research Publications

Fiber Reinforced Composites in Pediatric Dentistry

Contributing Authors

Dr. Gautam Kumar Kundu Prof & Ex -HOD.

Dr. Shabnam Zahir Prof & HOD.

Dr. Biswaroop Chandra Ass. Prof

Dr. Pratik Kumar Lahiri Ass. Prof.

Dr. Sudipta Kar Ass. Prof.

Dr. Rajib Saha Senior Lecturer.

Dr. Piyali Datta Senior Lecturer.


Medical and Research Publications

Copyright © 2021 Dr. Sunita Agarwalla, et. al.

All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in

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quotations in a book review..

First printing, 2021.

Published by

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ACKNOWLEDGEMENT

First and foremost, praises and thanks to the God, the Almighty, for His showers of

blessings throughout my work to complete the work successfully.

It is a humbling experience to acknowledge those people who have, directly or indirectly

contributed towards my work. I am indebted to so many for encouragement and support.

My sincerest thanks are extended to my mentor, Dr. Biswaroop Chandra (MDS) Reader, Dept of

Pediatric & Preventive Dentistry, GNIDSR for his encouragement and guidance. I shall forever

be grateful for the constant encouragement and fruitful criticism which he has bestowed upon me

in carrying out this work. His brilliant foresight and practical approach has been a guiding force

behind all my efforts in bringing this book to its ultimate goal.

I wish to convey my profound gratitude to Prof. (Dr.) Gautam Kumar Kundu Professor, Ex-Head

of the Department, Dept of Pediatric & Preventive Dentistry, GNIDSR and Prof. (Dr.) Shabnam

Zaheer (M.D.S), Professor, Head of the Department, Dept of Pediatric & Preventive Dentistry,

GNIDSR for their constant support and encouragement.

I owe a deep sense of gratitude to all my teachers Dr. Pratik Kumar Lahiri MDS, Dr. Sudipta

Kar MDS, Dr. Rajib Saha MDS, Dr. Piyali Datta MDS for their valuable guidance and

constructive criticism.

I am extremely grateful to my parents for their love, prayers, care and sacrifices for educating

and preparing me for my future. I am very much thankful to my husband and my daughter for

their love, understanding, prayers and continuing support to complete this work. Also I

express my thanks to my sisters, brother, and brother in law for their support and valuable

prayers.

Foreword

Let me start this writeup with a famous quote of C.S.Lewis

"You are never to old to set another goal or to dream a New Dream"

Its my privilege to say few words on this book.

Use of composite in restorative dentistry is constantly evolving. Reinforcement of Composite with

fibre has come up with variety of additional clinical applications.In this book Sunita has left

no stone unturned to update readers on different clinical possibilities which will help not only the

academicians but also the clinicians.

I wish all success of this endeavor though I believe in the famous quote of Winston Churchill

Success is not final,failure is not fatal: it is the" courage to continue " that counts.

Maintain this "Courage to continue".

Prof.(Dr)Gautam Kumar Kundu

Ex HOD,Dept.of Pediatric and Preventive Dentistry.

GNIDSR,KOLKATA

Dedicated to…

Gopal and Khanak who always inspire me and make me

so proud…

Without whom this work would not have been possible.

CONTENTS

S.No Chapter Pg.No

1. Introduction 1

2. History 6

3. Applications for Fiber Reinforced Composites Outside Dentistry

11

4. Definition and Classification of Fiber Reinforced Composites

12

5. Mechanical Properties of FRCs 16

6. Properties of Fibre Reinforced Composite 23

7. Biocompatibility 25

8. The Clinical Applications of Fiber Reinforced Composites in All Specialties of Dentistry

29

9. Clinical Applications in Conservative Dentistry 31

10. Fiber-Reinforced Composite as A Post and Core Material In A Pediatric Dentistry)

43

11. Clinical Procedure 62

12. Surgical Applications for Fiber Reinforced Composites

80

13. Bibliography 84


1

INTRODUCTION

The dental restorative materials are considered as a unique class of biomaterials with some

restrictions in physical, mechanical and biological properties like biocompatibility, aesthetics, and

material properties. Examples include Amalgam, composite resin, glass ionomer cement, resin

modified glass ionomer cement (RMGIC), compomers which fall under the direct restorative

materials. The indirect restorative materials include porcelain (ceramic), composite resin, ceramic-

resin hybrids, gold, other historical fillings such as platinum, aluminium, tin and iron, thorium,

lead and tungsten etc. In recent years the dental restorative materials are the main target of an

excellent deal of research with the goal of improving restoration performances by changing the

initiation systems (composite), fillers (GIC) and by developing novel polymerization strategies

(composites) etc.1

Despite better understanding of the materials and recent improvements in physical

properties, no material has been found that is ideal for any dental application. Silver amalgam has

been used for dental restoration for more than a century; however, there has been a serious concern

about mercury toxicity from the amalgam restorations for several years. Another major concern is

the color of amalgam for aesthetic considerations and alternative materials are being sought to

replace. The composite restorative materials have promising esthetics however these materials are

very technique sensitive and mechanical properties are not as good as of amalgam. Restorative

dentistry is constantly evolving as a result of innovative treatment procedures based on new

materials, treatment techniques and technologies, with composite materials being a key example.1

As popular and successful as these materials are, they exhibit shortcomings that frequently

cause clinical problems:2

1. The metal alloys used to make substructures that reinforce crowns and fixed prostheses

are strong and rigid, but they are not esthetic as given in figure below. Furthermore, the

base metal alloys commonly utilized in clinical practice may corrode and a few patients


2

have an allergy to them. Certain components of some base metal alloys may even cause

acute and chronic health hazards to laboratory personnel.

2. Ceramic materials such as porcelain may exhibit good optical qualities, but they are also brittle

and hard, they have the potential to lose structural integrity, and they sometimes abrade or fracture

the opposing teeth.2

3. The porcelains used to mask the metal substructure are opaque, unesthetic and require a

minimum thickness of coverage to obtain an acceptable result. Use of hard, brittle porcelain veneer

results in severely abraded mandibular anterior teeth opposing the porcelain and porcelain-metal

junction of metal-ceramic crowns.

Unesthetic appearance due to metal exposure at

base of the crown

Source: James Fondriest 2019

Of te

Metal ceramic prosthesis prior to try in

appointment

Of te

Metal-ceramic FPD with a fractured porcelain veneer and

abrasion of opposing teeth


3

4. The acrylic polymer materials such as methyl methacrylate that are used to make removable and

provisional fixed prostheses offer desirable handling qualities and physical properties, but they are

susceptible to fracture in many clinical circumstances.2

The development of fibre reinforcement has further increased the potential uses of composite

resins in restorative dentistry. Fiber-reinforced composites (FRCs) are composite materials with

three main constituents: the matrix (continuous phase), the fibers (dispersed phase), and the zone

in between (interphase). FRC materials have high stiffness, strength and adequate toughness per

weight in comparision with other structural materials. The development of the fiber-reinforced

composite technology has brought a new material into the realm of metal-free adhesive esthetic

dentistry.3

FRCs have been used for various applications in various other fields like engineering and

biomedical for a long time. For more than 40 years, the reinforcement of dental resins with either

short or long fibers has been described in literature. Fiber-reinforced composites (FRC) are resin

based materials containing fibers aimed at enhancing their physical properties.

It has been suggested recently that resin bonded, glass fibre-reinforced fixed partial dentures

(FPDs) may be an alternative to resin-bonded FPDs with a cast metal framework. FRCs consists

of reinforcing component provides stiffness and strength surrounding matrix supports the

reinforcement and provides workability. The fibers routinely used in dental applications for

reinforcement are polyethylene, glass, polypropylene, carbon or aramid. The matrix comprises of

epoxy resin which maintains the position and orientation of the reinforcement and provides

strength and rigidity to a prostheses.

Different fiber types such as glass fibers, carbon fibers, Vectran fibers, Kevlar fibers, and

polyethylene fibers have been added to composite materials. Glass fibers, consisting of glass

Failure of PMMA polymer, with fractured maxillary complete.


4

interlaced filaments, improve the impact strength of composite materials. They have excellent

esthetic properties, but they do not easily stick to the resinous matrix.

➢ Carbon fibers prevent fatigue fracture and strengthen composite materials, but they have

a dark color that is esthetically undesirable. Kevlar fibers, made from an aromatic

polyamide, increase the impact strength of composites, but are not esthetic, hence their

use is restricted. Vectran fibers are synthetic fibers which comprises of aromatic

polyesters. They show acceptable resistance to abrasion and impact strength, but are

expensive.

➢ However, polyethylene fibers improve the impact strength, modulus of elasticity and

flexural strength of composite materials. When compared to other fibers, these fibers

almost invisible in the resinous matrix.

➢ Due to these reasons, they are the most appropriate and the best esthetic strengtheners of

composite materials.

➢ The use of this fiber is based on the clinical reports of tooth replacement by Bradenstein

and Sperber, Marcus, and Millerand Portilla, among others.4

➢ This fiber has been described as being used for perio splints,strengthening removable

prosthesis, post and core fabrication, and provisional use.

➢ Fiber-reinforced materials have highly favorable mechanical properties, and their

strength-to-weight ratios are superior to those of most alloys.

➢ When compared to metals they offer many other advantages as well, including non

corrosiveness, translucency, good bonding properties, and ease of repair.

➢ Since they also offer the potential for chairside and laboratory fabrication, it is not

surprising that fiber-reinforced composites have potential for use in many applications in

dentistry.3


5

Because of the ability to manipulate the properties of composites to match with structural

aspects, fiber reinforced composites (FRCs) have many clinical applications in dentistry. In

Additionally, the mechanical properties of FRC are often optimized to equal that of bone or dentin.

This unique property has been tailored for dental needs by designing frameworks for crowns,

anterior or posterior fixed prostheses, chair side tooth replacements, posts and appliances like

space maintainers, periodontal splints and orthodontic retainers.4

➢ Dental caries is the most common chronic disease in childhood despite the fact that it is

largely preventable. The caries may take a toll and may result in total destruction of the

dental elements in cases like early childhood caries.

➢ The oral rehabilitation of these teeth is a great challenge for pediatric dentistry. Until very

recently, for early childhood caries the only treatment option was extraction of the

affected primary anterior tooth, which resulted in severe coronal destruction .

➢ The early loss of primary anterior teeth may result in reduced masticatory efficiency, loss

of vertical dimension, development of parafunctional habits (tongue thrusting, speech

problems), esthetic functional problems such as malocclusion and space loss, and

psychological problems which might subsequently lead to personality and behavioral

problems in children at a later stage.

➢ Various restorative treatment options are pre-fabricated crown and biological and resin

composite restoration either by means of direct or indirect techniques mentioned in the

literature.

➢ Reinforcement fibers (polyethylene fibers) were recently introduced and can be used as

an intra-canal retainer associated with the resin composite as an alternative option for

reconstruction of primary incisors greatly damaged by an extensive carious lesion.

➢ A more recent approach has used composite alone or in combination with other

reinforcement material, and the use of fiber set in composite resin resulted in an increase

in the strength of restoration.5


6

HISTORY

➢ Fiber reinforced composite (FRC) group of materials have been in use and tested since

1960s but for dental use developed and clinically approved materials are available more

extensively during the last 30 years and for the medical implant use during the 15 years.

➢ The initial attempts for using fiber reinforcement in clinical dentistry began more than

35 years ago. In the 1960s and 1970s, investigators sought to reinforce standard

polymethyl methacrylate dentures with glass or carbon fibers.

➢ In the 1980s, similar attempts were repeated, and initial efforts were made to fabricate

fiber-reinforced prosthodontic frameworks for implants, fixed prosthodontics

restorations, orthodontic retainers, and splints.2

➢ While these materials and techniques demonstrated improved mechanical properties,

they failed to achieve general clinical acceptance because of insufficient enhancement of

properties and awkward clinical manipulating procedures.

➢ Almost all the procedures advocated involved automatic manual placement of fibers into

dental resins that were otherwise processed with routine methods.

➢ But this approach was inconvenient because free fibers are difficult to handle and utmost

care must be taken to avoid either damaging or contaminating them.

➢ Even though the addition of fibers increased mechanical properties, the degree of

improvement achieved was far below other commercial applications.

➢ There were two main reasons for the lower-than-expected mechanical results.

➢ First, the actual amount of fiber incorporated into the dental resins was low, typically

less than 15% by volume. (Industrial products may contain 50% or even as much as 70%

fiber by volume.)


7

➢ Second, as stated in theory the fiber reinforcement was not very effective due to the poor

wetting of the fiber bundles by the resin which led to insufficient coupling and gaps

between the fibers and resin.

➢ During testing, it was found that effective coupling usually results in failure within the

matrix not at the fiber-matrix interface.

➢ Clinical uses and whether the fiber bundles are pre-impregnated with resin by the

manufacturer or resination is required by the dentist or laboratory technician. 2

➢ Though there is wide variation between products in fiber surface treatments, dental

manufacturers use only standard industrial fibers; methods for incorporating the fibers

into the polymeric resin, and chairside and laboratory processing methods.

➢ Towards the end of 1980s, dental researchers found the importance of effective coupling

and complete impregnation of the fiber bundles by the resin and started developing

techniques applicable for dentistry.

➢ Since then two approaches have evolved. In the first technique, manual application of a

low viscosity resin to the fiber bundles is done by the dentist or laboratory technician. It

provides complete wetting, Though it provides versatility in the selection of fibers and

resin, this approach can be cumbersome and requires an additional step in the procedure.

➢ The other approach is to use pre-impregnated fiber bundles during a controlled

manufacturing process.

➢ There are numerous manufacturing parameters which regulate the final fiber dimensions

and content, the viscosity of the resin, speed of the process, tension on the fiber bundles

etc.


8

➢ These complex process parameters allow for high fiber content, complete wetting,

minimum void content, and control of the cross-sectional dimensions in pre-impregnated

FRCs.2

➢ Some of the earliest of these experimental pre-impregnated FRCs designed for dental

applications were based on glass-reinforced thermoplastics.

➢ Clinical trials were conducted using glass-reinforced polycarbonate as orthodontic

retainers. The function of esthetic retainers is satisfactory and the mean service life of

20.4 months.

➢ Most importantly, only 6% of those that failed were due to frank mechanical breakage of

the fiber composites, confirming that the physical properties of these materials are

adequate for this clinical application. The cause of most of the clinical failures was

debonding of the retainers from the tooth surface.

➢ A successive clinical trial evaluated the application of pre-impregnated glass-reinforced

polycarbonate as the framework for acid-etched fixed partial dentures (FPDs).

➢ 14 three unit restorations were placed both in anterior and posterior region using adhesive

techniques and without any tooth preparation.

➢ After 9 years, three restorations were still in place. Eleven failures were caused by

separation in the region of the tooth restoration interface and none was due to frank

mechanical breakage of the fiber-reinforced framework.

➢ The clinical failures mainly occurred at the adhesive-tooth interface, the adhesive–fiber

composite interface, or within the outer matrix of the fiber-reinforced composite.

➢ This study established the acceptable mechanical properties of FRCs for use in

prosthodontics and it also confirmed that it is difficult to manipulate the thermoplastic

resin matrix and offers poor bonding to tooth structures.2


9

➢ These problems were overcome by switching to a bisphenol glycidyl methacrylate (bis-

GMA) based resin as the matrix for the FRCs.

➢ 4 year clinical trials of carbon fiber–reinforced polymethyl methacrylate implant-

supported prostheses also demonstrated the potential for prosthodontic applications.

After 4 years, only 5 (19%) of 27 original prostheses had fractured; however, these

experimental materials had less than half the strength of the commercial materials

currently used.

➢ Recent laboratory studies of provisional restorations have demonstrated that proper

reinforcement with woven polyethylene fiber or glass fiber improves fracture resistance.

➢ Continued research on glass-reinforced bis-GMA systems, combined with important

manufacturer-designed fiber impregnation and packaging systems, has led to the

commercial pre-impregnated systems available today: Sculpture/FibreKor, Splint-It

(Jeneric/Pentron); and Targis/Vectris (Ivoclar).

➢ The fiber-reinforced strips in both systems measured several millimeters in cross section

and several centimeters in length and packaged in separately sealed, light-tight

containers.

➢ Using either pre-impregnated or hand-impregnated strips, a dentist or technician forms

and fabricates the desired restoration, splint, or appliance, which is then cured.2

Glass fiber-reinforced polycarbonate orthodontic retainer


10

➢ For most of the FRC procedures, a direct or indirect method can be used. Splints are

commonly fabricated with a direct approach and light-cured, while to minimize chair time

and to allow for optimum esthetic and mechanical results fixed prostheses are typically

fabricated by dental laboratories.

➢ Both hand-impregnated and pre-impregnated systems are commercially available to the

laboratory, although the latter are more widely used.

➢ Two commercial pre-impregnated systems are available for dental laboratories. Both use

fiber composites to fabricate the framework, and the final tooth shape is then built with

particulate reinforced restorative composite.

➢ One system, Sculpture/FibreKor (Jeneric/Pentron), uses hand fabrication to form the

framework and con-dense the strips .2

➢ The other system, Targis/Vectris (Ivoclar), uses custom-made matrices and special

equipment to apply pressure to the fiber strips during fabrication.

➢ The primary aim in the fabrication of the framework are to incorporate adequate amount

of fiber reinforcement, reduce voids and confirm strong bonding between both the layers

of pre-impregnated fiber strips and restorative composite and the fiber framework in both

systems,.

➢ Clinical trials of the commercial systems, now in their third year, demonstrate satisfactory

performance when appropriate designs, fiber volume, and manipulative procedures are

followed, although a loss of surface luster was often observed soon after placement.

➢ The initial designs of fiber-reinforced FPDs required substitution of the facings, however

repair techniques have been described to minimize or eliminate the need to replace the

complete restoration.


11

APPLICATIONS FOR FIBER REINFORCED

COMPOSITES OUTSIDE DENTISTRY:

➢ Fiber-reinforced composites (FRCs) have the potential to remedy many of the structural

andesthetic problems described above.

➢ Though the use of these materials is new to dentistry, but they have found application in

a number of industries outside dentistry because of their many advantageous properties.

➢ Recreational boat hulls (Fig:2A) as well as many other components used in the

boatingindustry, such as masts and rudders, are now routinely made with FRCs.

➢ High-quality buses and large modern windmills (Fig:2B&C) are also made with fiber-

reinforced materials. 2

➢ Fiber-reinforced materials have good overall mechanical properties, and their strength to

weight ratios are superior to those of most alloys.

➢ The additional features that make these materials advantageous compared to metals are-

noncorrosive properties, potential translucency, radiolucency, good bonding properties,

and ease of repair.

➢ Given that they also offer the potential for chair side and laboratory fabrication, it is not

surprising that FRCs have many applications in dentistry.2

Fig 2A: High-quality sailboat made

with glass fiber–reinforced hull

Fig 2B: Glass fiber reinforced bus Fig 2C: Modern windmill with fiber

reinforced blades


12

DEFINITION AND CLASSIFICATION OF FIBER

REINFORCED COMPOSITES:

• Fibre-reinforced composite restorations are resin-based restorations containing

fibres aimed at enhancing their physical properties.

• The nature of the fibre, the geometrical arrangement of the fibres and the overlying resin

used makes this group of materials is very heterogeneous

• An adhesive interface allows the fibres within the composite matrix to bond to the resin.

The main factors that influence the physical properties of FRC structures are listed as follows:

• Fibre loading (volumetric fraction) within the restoration;

• The fibre-resin interface bond efficacy;

• Fibre orientation relative to load;

• Fibre position in restoration3


13

CLASSIFICATION:2 Fiber reinforced composites can be

classified as follows:

ADVANTAGES AND DISADVANTAGES OF FRCs:

ADVANTAGES

• Lower treatment costs.

• Single visit immediate tooth replacements.

• Appropriate for long-term and transitional provisional restorations.

• Readily repaired.

• Suitable for young patients (developing dentition) and elderly (time saving).

• Metal free restoration.

• Improved aesthetics.

• Can be produced in a simple manner in the laboratory without the need for waxing,

investing and casting.


14

• Can be routinely used with minimal or no tooth preparation.

• Minimize abrasion of the opposing teeth in comparison to conventional metal-ceramic

restorations.

DISADVANTAGES

• Potential wear of the overlying veneering composite especially in patients with significant

parafunction.

• May lack sufficient rigidity for long span bridges.

• Excellent moisture control required for adhesive technique.

• To allow sufficient room for fibres and adequate bulk for veneering composite overlay,

space requirements are greater in posterior occlusal situations in comparison to metal

occlusal surfaces.

• Uncertain longevity in comparison to traditional techniques.3

COMPOSITION, ARCHITECTURE, AND MECHANICAL PROPERTIES

OF FIBER-REINFORCED COMPOSITES4

• Fiber-reinforced composites (FRCs) are structural materials that have at least two distinct

constituents.

• The reinforcing component imparts stiffness and strength, whereas the encompassing

matrix supports the reinforcement and provides workability.

• In dental applications, one of the constituents may be metal, ceramic, or polymer,

polymeric or resin matrices reinforced with glass, polyethylene, or carbon fiber are most

common.

• Usually, fibers are 7 to 10 pm in diameter and span the length of the prosthesis or appliance.

The particle size used in standard restorative dental composites are 1 to 5 pm in diameter,

or submicron. The fibers may be arranged in various configurations: unidirectional fibers

—continuous, long and parallel—are the most popular, followed by braided and woven

fibers.


15

• The type of fiber used to make an FRC depends on how it is intended to be used and the

characteristics that are needed for that purpose.

• Glass fibers of various kinds are commonly used in dental laboratory products, while

polymeric reinforcements, such as polyethylene, are often used for chairside applications.

Posts are made of carbon or glass fibers.

• Table below (table:2) lists different types of fiber and the important mechanical and

physical characteristics of each. The types of fiber and architecture found in various

products products are classified according to their clinical uses and whether the fiber

bundles are pre-impregnated with resin by the manufacturer or resination is required by the

dentist or laboratory technician.4


16

DIFFERENT TYPES OF FRC PRODUCTS ACCORDING TO FIBER TYPE

AND ARCHITECTURE: Table:2

Scanning electron micrographs of glass-reinforced thermoplastics showing the degree of

wetting of the fibers by the matrix:2

MECHANICAL PROPERTIES OF FRCs:

➢ Mechanical properties in the matter of strength, toughness, stiffness and fatigue resistance

rely upon the geometry of the reinforcement. The provision of strong fiber resin interfaces

contributes to greater static and fatigue properties.

➢ Increased hardness and tensile strength are influenced by the incorporation of silanated

filler particles of fiber (Debnath et al., 2004).


17

➢ The effectiveness of the fiber reinforcement, as described on theKrenchel’s factor, differs

according to the length and fiber orientation.

➢ The reinforcing efficiency factor for the fiber reinforcement goes against the known

direction of stress (Krenchel 1963).

➢ Many other parameters contribute to the reinforcing efficiency offibers, between them

interfacial adhesion, fiber volume fraction and elongation of fibers (Murphy, 1998).

➢ Fiber-reinforced composites are classified as short discontinuous and long continuous

FRCs. They show differences in their mechanical properties even when their fiber volume

fraction is similar (Kardos 1993).

➢ For instance, if continuous unidirectional fibers are replaced by longitudinally oriented

discontinuous short fibers of lower aspect ratio, a reduction of the ultimate tensile strength

of the composite will be the result (Vallittu, 2015).4

➢ The isotropicity-anisotropicity of the material plays a role. Continuous and discontinuous

FRCs are anisotropic and they become isotropic when the orientation of short fibers is

random, with the outcome of reducing the tensile strength.

➢ In a polymeric structure the provision of fiber reinforcement increase its modulus of

elasticity or stiffness and toughness (Wright et al., 1997).

➢ The modulus of elasticity (E) is a measure of the stiffness, defined by the slope of the

stress-strain curve linear segment before plastic deformation.

➢ According to that, a direct influence exists between the E and the stiffness, providing that

the higher the E, the stiffer the material will be.

➢ The greater the E, the less the elastic deformation will be as a resultant of the stress

application.

➢ Toughness is the ability of a material to absorb energy and have the capacity to plastically

deform without fracturing (Callister, 1991). Some investigations have been focused on the

effects of fracture toughness and E on FRCs.

➢ One of them found that the E of particulate reinforced composites increases when cross-

sectional designs included 1 or more fiber reinforcements located at the compression side

(Dyer et al 2005).4


18

ADHESIVE INTERFACE:

➢ The adhesive interface transfers the load from the polymer matrix to the reinforcing fibers,

which positions this interface as a key aspect for the durability of FRCs (Bouillaguet et al.,

2006).

➢ A chemical bond is achieved between the polymer matrix and the exposed glass fibers due

to the use of silane coupling agents.

➢ The abilities of silanes to enhance the surface wettability of the glass fibers, resulting in

chemical bridges formation and an increased physical attachment of the resin to the surface

of glass have been reported in some studies. (Goracci et al., 2005).

➢ Some other aspects have an effect on the durability of FRC restorations, for instance, the

properties of the fibers; resin matrix; the quantity of fibers; the direction, orientation,

distribution, construction and position of the fibers and the impregnation of the fibers with

the resin (Pensler etal., 1997).

➢ Two types of resins are used in FRCs, forming a cross-linked (thermoset) Polymer matrix,

or a linear (thermoplastic) polymer matrix. Multifunctional or dimethacrylate resins are

involved in the formation of the cross-linked matrix, contrary to the non-crosslinked

polymer matrix where monofunctional methacrylates are included (Vakipartaet al., 2007).

➢ A combination of thermoset and thermoplastic resins has been used as impregnation

methods. In this case, the polymer matrix is a semi-interpenetrating polymer network (semi-

IPN), where a cross-linked polymer and a linear polymer are merged(Kallio et al., 2001). 6

➢ Cross-linked polymer matrix results in FRCs with higher modulus of elasticity than the

achieved by thermoplastic or semi-IPN polymers (Lassila et al.,2002).

➢ Additionally, higher toughness is one of the advantages that thermoplastic and semi-IPN

polymer matrices contribute over FRCs manufactured from highly cross-linked thermosets.

➢ The semi-IPN polymer matrix of FRC provides some benefits over crosslinked

dimethacrylate regarding its handling properties and the adhesion of indirectly made

restorations to resin luting cements and veneering composites (Kallio et al.,

2001).Polyethylene (PE), polyetheretherketone (PEEK), polyacetal (PA), and polyurethane

(PU) are examples of thermoplastics that are used in medical applications of thermosets are

epoxy polymer, bis-GMA, and TEGDMA copolymer (Tuusa et al.,2007).


19

Rule of Mixtures

➢ In prosthodontic applications, the two most important mechanical properties for FRCs are

strength and stiffness. The modulus of elasticity refers to stiffness or rigidity of the material.

➢ For fiber-reinforced FPD frameworks a high modulus is necessary because they must

support the more brittle overlying restorative composite. This situation is comparable to

metal frameworks supporting porcelain in a metal-ceramic prosthesis.

➢ In an ideal unidirectional FRC, the modulus as well as the strength in the fiber direction is

proportional to the volume and individual properties of the fiber and the matrix. This

relationship is known as the rule of mixtures.2

➢ The rigidity and strength of a unidirectional fiber composite are significantly dependent on

the properties and volume of the fiber as the properties of the fiber are generally much

greater than those of the matrix,

➢ Large volumes of high-strength unidirectional fibers are desirable when the highest

mechanical properties are desired in a single direction, as in a post or in the pontic region

of an FPD framework,

➢ Areas where esthetics may not be of concern, carbon fibers may be used. Glass fibers are

generally preferred where translucency is required along with good mechanical properties.

➢ Fiber volumes are generally limited to less than 50% because of the necessity of having all

fibers fully wetted by the resin. Classic pre-impregnated unidirectional dental fiber

composites incorporating approximately 45% glass fibers have a flexure modulus in the

range of 28 to 34 GPa and flexure strengths of about 600 to 1,000 MPa.

➢ These values are about 10 times greater than those for dental resin alone, and they represent

the primary mechanical benefit of using fiber reinforcement in dentistry.


20

How FRC Materials Work

➢ Several parameters influence the mechanical performance of FRC. Increasing fiber volume

leads to a greater increase in mechanical strength. The fiber architecture: unidirectional

fibers long, continuous, and parallel followed by braided and woven fibers also increase

flexural strength b van Hueman.4

➢ Typically, fibers are 7 to 10 μm in diameter and span the length of the prosthesis or appliance

whereas the size of the particles used in standard restorative dental composites are 1 to 5

μm in diameter, or submicron in size.

➢ Glass fibers of various kinds are commonly used in dental laboratory products, while

polymeric reinforcements, such as ultra high molecular weight polyethylene, are often used

for chair-side applications. Posts are made of carbon or glass fibers.

• Woven fiber has lesser flexural strength and is less technique-sensitive, and easy to manipulate

thus conforming to the desired shape and maintains its adaptation during placement and is the ideal

choice while making an appliance for rotated or malpositioned teeth.

• Unidirectional fiber has greater flexure strength and rigidity and is the better choice for high

stress situations as in prosthodontic frameworks.4


21

The Two Approaches have Evolved Namely Non-Impregnated and

Pre-Impregnated

Non Impregnated :

Non-impregnated are the fibers that needs to be wetted with an unfilled fourth or fifth

generation bonding resin at chairside. A partially filled bonding resin is not recommended to wet

the Ribbond as they are more viscous and hence are not self wetting. While it provides complete

wetting, this approach can be cumbersome, requires an additional step in the procedure and

displays limited service as splints. However, this method can be considered versatile.

Pre-Impregnated Fibers :

➢ Clinical longevity of non-impregnated fibers is compromised as it lack good adhesion

between the fiber and resin matrix compromising and freshly drawn glass fibers exhibit

higher strength than ordinary glass fibers but are rapidly degraded on exposure to moisture

and humidity.4

➢ As these fibers with resin maintains the high strength values if coated immediately, the

concept of pre-impregnation of glass fibers evolved (Splint-it). This procedure is

accomplished by pre-impregnating the fiber bundles with resin during the manufacturing

process.

➢ Pretreatment of glass fibers are done with organo-silanes and polyethylene fibers are

subjected to cold gas plasma treatment to increase their wettability and chemical bond. E-

glass and S-glass are two types of glass fibers of which E-glass is employed in dental

materials. Another type used is C-glass mainly used in chemical applications that requires

greater corrosion resistance to acids than is provided by E-glass.


22

IMPREGNATION OF FIBERS:

➢ Resin impregnation allows an optimal reinforcement and transfer of stresses from the

polymer matrix to the reinforcing fibers (Vallittu, 1998b).

➢ Effective impregnation is a requirement to achieve a good contact between the matrix and

each fiber, which isoften performed using various monomers. Some of these monomers are

bis-GMA,UDMA, urethane tetramethacrylate (UTMA), poly(methylmethacrylate) (PMMA)

ortriethylene glycol dimethacrylate (TEGDMA) (Lastumäki et al., 2003).

➢ The use of only monomers for the impregnation of fibers brings as a consequence a high

polymerization shrinkage, which may affect the mechanical properties of the FRC (Vallittu,

1996).

➢ Then, pre-impregnated FRC systems have been developed, which facilitates the handling

properties.

➢ Deficiencies in the impregnation of fibers increase the water sorption in FRC, reducing their

strength and modulus of elasticity (Miettinen et al., 1999).

➢ The use of high viscosity resin systems and the polymerization shrinkage of the resin can

have as consequence an inadequate degree of impregnation of fibers (Vallittu 1995a; Vallittu

1995b).

➢ This enhances water sorption through voids leading to decreased mechanical properties of

FRC (Miettinen & Vallittu, 1997). In addition, voids originated due to poorly impregnated

fibers serve as oxygen reservoirs that inhibit the radical polymerization of the polymer matrix

(Vallittu, 1999).

➢ Pre-impregnated FRCs also show good mechanical properties due to the reduction in voids

and cracks in its composition, which can limit water sorption. Water sorption due to poor

impregnation can have detrimental consequences in the bond strength and lead to hydrolytic

degradation of polysiloxane network of FRC (Miettinen & Vallittu, 1997).5


23

PROPERTIES OF FIBRE REINFORCED COMPOSITE

Water sorption:

➢ Water sorption of a material includes water absorbed into the body and water adsorbed on

the surface of the material during preparation and while the material is in service.

➢ Poly (methyl methacrylate) absorbs water because of the polarity of the water molecule

and because it is smaller than the inter chain distance in the polymer.

➢ The volume of water uptake by a polymeric material is determined by polymer structure,

content of various polar and hydrophilic groups in the polymer structure, temperature,

concentration of various additives, presence of voids within the matrix, Physicochemical

and mechanical properties can be affected by absorbed water.5

Flexure Strength:

➢ These materials are often tested in the laboratory, although the mode of failure and many

other properties affect clinical performance.

➢ Investigators accentuate the importance of fatigue and fracture toughness in predicting

clinical performance of several classes of dental materials, including fibre composites.

➢ It is important to note that test methods, procedures for preparing the samples, and, in

particular, the geometry of the test specimens all affect the calculated flexure strength.

➢ Flexure strength for commercial laboratory–processed fibre-reinforced composites may

range from approximately 300 to 1,000 MPa, depending on the specimen preparation and

geometry.

Fracture toughness:

➢ The fracture toughness of a material reflects the resistance of a material to fracture and

represents the energy required to propagate a crack through the material to complete

fracture.


24

➢ Fracture toughness of polymer composites depends on the type of polymer and

reinforcement. Fracture toughness of a monomethacrylate-based material is lower than in

a dimethacrylate-based material.

➢ Generally, “intrinsic” physical aging and/or storage in a humid environment at elevated

temperatures can decrease fracture toughness, as well as other mechanical properties.

However, an increase in fracture toughness can be achieved by adding reinforcing fibres

to a polymer to prevent or slow down crack growth.5

Linear coefficient of thermal expansion:

➢ The variation of the coefficient of thermal expansion between different materials is

important because a mismatch can lead to strains, resulting in stress formation and adverse

effects on the interface.

➢ Therefore, thermally induced strains and stresses adversely affect long-term stability of

intraoral multiphase materials. By adding fibres to a polymer, the coefficient of thermal

expansion decreases.

➢ Usually, the thermal coefficient varies with the direction of the fibres. The matrix is forced

to expand in the transverse direction as in a composite rigid fibres appear to prevent

expansion of the matrix in the longitudinal direction.

➢ One of the major concerns in the development of dental materials is physical and chemical

durability.


25

BIOCOMPATIBILITY

Solubility:

➢ Stabilizers, plasticizers, monomers, residuals of initiators and degradation products are the

components that may be released into the oral environment over time.

➢ Therefore, the amount of such components should be as small as possible to ensure that no

components adversely influence biocompatibility and the polymer retains its characteristic

properties.

Residual monomer:

➢ Biological features, as well as mechanical properties, of polymeric materials are highly

influenced by the monomer-polymer conversion.

➢ Residual monomer will alter the property and may leach out to pulp if a protective layer of

base is not given.5

Cytotoxicity:

➢ Some substances released from materials are cytotoxic and residual monomers leached out

into the oral environment may induce toxic and allergic reactions.

Polymerization shrinkage:

➢ The increased awareness among clinicians to protect and reinforce the remaining sound tooth

structure and gradual improvement in adhesive systems resulted in the increased use of

particulate filler composite resin materials (PRFC) both at the anterior and posterior regions.

➢ Despite the continuous improvement through modifications in formulation, polymerization

shrinkage seems to be a problem for the PRFC.

Various steps have been undertaken to evaluate and improve restorative composite resin against

wear and lower the polymerization shrinkage. Attempts have been made to change type and size

of filler and their silanization. Also attempts to change the polymerization kinetics of resins and to

influence to degree of monomer conversion. Reinforcing the resin with glass fibres with fibre-

reinforced composite (FRC) substructure and optimization of filler content are among the methods

that have been studied.


26

THE MATRIX IN FRCS

➢ The fibers in the composite structure are held together by the polymeric plastic matrix

composed of polymerised monomers. It protects the fibers from the external environment such

as moisture, chemicals and mechanical shocks and transfers stresses between fibers.

➢ Therefore the matrix may have an impact on the compressive strength, interlaminar shear and

in-plate shear properties, interaction between the matrix and the fiber and defects in the

composite. 6

➢ Two types of resins namely the cross-linked or linear, are used in FRCs. The cross-linking

polymer referring to multifunctional or dimethacrylate resins is also called a thermoset

polymer. The linear polymer referring to monofunctional methacrylate polymers is also called

a thermoplastic polymer.

➢ The matrix consists of a cross-linking polymer, a linear polymer and a photo-initiator

with an interpenetrating polymer network (IPN) structure in FRCs. Polymerization

reactions and cross-linking reactions are the setting reactions in the resin matrix. Sequential

addition of monomeric units leading to the formation of a polymer by is a polymerization

reaction.

➢ Addition (including free-radical addition polymerisation) and condensation polymerizations

are the main polymerization reactions. The cross-linking reaction in a polymer is the

formation of a cross-link where chains are bonded together either through direct connection

or an intermediary atom, ion, molecule or chain. This produces a 3D strongly cross-linked

system.

FIBER:

➢ A fiber may be described as an elongated uniform material with a more or less equiaxed and

uniform transverse cross sectional diameter or thickness less than 250 μm, and with an aspect

ratio, i.e. length to cross-sectional diameter or thickness ratio, which is usually greater than

about 100.

➢ However, in some cases, such as short fibers, chopped fibers, or staple fibers, the fibers’ aspect

ratio can be smaller than 100.


27

➢ For the reinforcement and clinical success the fiber orientation, content, distribution and the

ability to maintain these parameters are significant.

➢ The type, length, orientation and volume fraction of the fiber influence the following

properties of the FRC: their tensile strength and modulus, compressive strength and modulus,

fatigue strength and fatigue failure mechanism, density, electrical and thermal conductivity,

and finally their cost. 6

➢ Glass, polyester, polyethylene, carbon/graphite, aramid, quartz and ceramic fibers are the

commonly used fibers.

ADHESION BETWEEN FIBER AND MATRIX

➢ Silanes are hybrid inorganic-organic chemical compound in which a carbon is directly attached

to silicon, eg. ≡Si–C≡. These silicon esters are used as coupling agents in silanization

treatment, often called as silanation. This refers to bonding of dissimilar matrices together with

surface treatment.

➢ Preimpregnation means that the fibers are impregnated with the matrix resin before further

steps in the fabrication of the final restoration in dentistry. Highly porous linear polymers are

used to preimpregnate the fibers as described in of the current preimpregnation based fiber

reinforcement system.

➢ This is why the high-viscous denture base resin is subjected to further impregnation.

➢ The use of natural rubber and thereafter synthetic polymers as denture base polymers had

already started in the 1860s.

➢ With the introduction of crosslinking thermoset monomers in dentistry by Bowen, crosslinking

dimethacrylate monomers became available also for monomer liquids of denture base resins

and, thus, in multiphase denture base polymers—the start of the use of interpenetrating

polymer network (IPN)-like structures in dentistry.

➢ As a concept, an IPN is a combination of two or more polymers in network form that are

synthesized injuxta position. IPNs are composed of finely divided phaseswith a thickness of

approximately 5–10 nm.6

➢ They differ from polymer blends which are rougher in structure, and also differ from

copolymers which are based on chemical reactions of monomer units and polymer backbones.

➢ Several adhesive interfaces between natural and synthetic biomaterials and adhesive resins by

means of primers or coupling agents can also be considered as IPNs.


28

➢ Some other interfaces are a dentine bonding hybrid layer, silane promoted adhesive interphases

between metal and ceramics and adhesive resins.

➢ On the other hand, the so-called semi-IPN refers to the impregnation methods based on using

a combination of thermoset and thermoplastic types of resins. Here, the polymer matrix is a

multiphase material.

➢ The semi-IPN is formed during the polymerization of the dimethacrylate monomers with a

swelled linear polymer, PMMA.

➢ In addition to the above methods, plasma-etching has also been applied to enhance

polyalkanefiber’s adhesion to the matrix.

➢ It is also noteworthy that durable adhesion between fiber and matrix provides good load

transfer between the two, which ensures that the load is transferred to the stronger fiber and

this is how the fiber works as a reinforcement.

➢ Hardness is a surface phenomenon influenced by yield strength, true tensile strength, work

hardening, elastic modulus and so on.

➢ Brinell, Vickers, Knoop, Rockwell, Rockwell superficial and Shore scleroscope are various

standard testing methods for hardness.

➢ Flexural strength refers to the maximum stress and strain at the surface of the specimen and a

measure of the stiffness during the first or initial step of bending a body (material) is flexural

modulus.

➢ It is calculated according to an ASTM D-790 standard: mathematically it is the slope of the

initial straight line portion on the stress–strain curve.

➢ In laboratory experiments, several factors have effects on the flexural properties. Previous

research shows that thermo-cycling, the brand of the FRC material and diameter of the

specimen may have a significant effect (p<0.001) on flexural strength of FRC root canal posts.

Furthermore, fatigue strength refers to the stress that causes failure after some specified

number of loading cycles.

➢ In the aspect of fatigue strength, FRCs are considerably stronger than typical cast metal alloys

used in dentistry.

➢ In clinical use, biomechanical properties of dental materials vary depending on which

application the material is utilized. For instance, in a direct fibre-reinforced resin-bonded

dental bridge, the weakest region exists across the pontic–abutment interface.


29

THE CLINICAL APPLICATIONS OF FIBER

REINFORCED COMPOSITES IN ALL SPECIALTIES OF

DENTISTRY5


30

VERSATILITY OF FRC IN VARIOUS DENTAL

SPECIALITIES

➢ The properties of fibre-reinforced composites (FRCs) that make them well suited for

various clinical applications include strength; desirable aesthetic characteristics; ease of

adaptability to various shapes; and potential for direct bonding to tooth structure.

Restoration:

➢ Modern adhesives successfully bond to tooth tissue in the short as shown in laboratory

reports. Adhesives that provide strong and durable bonding to the remaining sound enamel

and dentin ensures restoring teeth with minimal loss of sound tooth structure.

➢ Marginal deterioration of composite restorations remains major disadvantage in the long

term and still is the major reason to replace adhesive restorations clinically.

➢ The initial and residual polymerization stresses that are present along the cavity walls may

result in gap formation, leakage, recurrent caries and pulp irritation when resin composite

is bonded to tooth structure.

➢ Along with aesthetics, the physical properties of restorative material should also be

considered for long-lasting restoration. Fibre reinforcement has been introduced as a newer

technique with the aim of improving the physical properties of composite materials.

➢ High fracture resistance of the restorative material is required in the clinical situations

where the high impact stresses are experienced and incisal angle restoration is one such

demand.

➢ Attempts have been made to improve the fracture resistance of restoration by using

different bonding agents, adhesive resins and different restorative techniques using fibre

reinforced technique.7


31

CLINICAL APPLICATIONS IN CONSERVATIVE

DENTISTRY

➢ The applications of FRCs in conservative dentistry mainly consist of direct composite

restorations. The advantages of the use of FRCs over conventional filling materials are

related to their biomimetic properties.

➢ In fact, the dental restorations ideally would be as minimally invasive as possible and

substitute the missing hard dental tissues resembling mechanical features and properties

of natural teeth.

➢ Research has shown that the FRC substructure supports the composite restoration and acts

as a crack-prevention layer when a bilayered approach has been proposed in which lost

dentin is replaced by though short FRCs and enamel by surface layer of particulate filler

composite resin in dental restorations.

➢ In addition, FRCs have been reported to have superior physical properties and fracture

toughness compared to unreinforced composites and depth of cure and polymerization

shrinkage of FRCs have been reported to be superior to conventional resin composites.

➢ On the other hand, bilayered biomimetic technique is recommended for direct coronal

restorations of teeth with large cavities in high stress-bearing areas.7


32

CLINICAL APPLICATIONS IN ENDODONTICS

➢ The use of FRCs in endodontics is mainly reported as root canal anchoring system.

Research on both prefabricated and individualized FRC posts demonstrated that root canal

walls restored with individually formed FRC posts displayed higher fracture resistance

than those restored with only resin composite.

➢ FRC posts both used in combination with self-adhesive and glass ionomer cements showed

promising bond strength to flared root canal dentin and FRCs achieved better

performances, even in combination with bulk fill resin composite.

➢ Mechanical properties of posts significantly decreased when compared with values at

baseline after aging as shown in various studies.

➢ Special considerations should be taken while bonding of luting cement and core-built-up

composite to FRC post: only FRC post with interpenetrating polymer network containing

polymer matrix can provide reliable bonding to resin luting cements and resin based

materials in general.

➢ Generally, FRCs present limited radio-opacity due to the low concentration of radio-

opaque elements. This shortcoming of E-glass fiber would limit its application in dentistry

as sufficient radio opacity is highly desirable for dental materials.

➢ The addition of synthesized iodine containing a new methacrylate monomer HMTIB has

been tested to increase the radio opacity of FRCs with the results showing that FRCs

present higher radiopacity than natural tooth enamel.

➢ Finally, in the field of endodontics, FRCs showed excellent integration with other new

technologies such as laser applications and CAD/CAM.7


33

Endodontic Fibre Reinforced Composite Posts:

➢ FRC posts are a recent addition to the systems traditionally used to retain a core in severely

broken down, endodontically treated teeth: custom-made metal or cast posts and cores and

prefabricated metal and zirconium posts.

➢ The FRC posts offer greater flexure and fatigue strength, a modulus of elasticity close to that

of dentin, the ability to form a single bonded complex within the root canal for a unified root

post complex, and improved aesthetics when used with all-ceramic or FRC crowns as

compared to custom-made cast or metal-prefabricated posts.

➢ The properties of this post design have the potential to reinforce a compromised root and to

distribute stress more uniformly on loading to prevent root fracture moreover, the FRC post

will yield prior to catastrophic root failure better than will custom- made cast metal or

prefabricated metal post systems.

➢ Two categories of FRC posts are available: chair side-fabricated and prefabricated. Chair side

fabricated posts are custom designs that use polyethylene non pre-impregnated woven fibres

(Ribbond, Connect) or glass fibres (Glass Span) to reinforce the root and hold a composite

core.

➢ Prefabricated posts are constructed of two kinds of fibre: carbon fibres embedded in an epoxy

matrix (C-Post, U-M CPost, and Aestheti-Post) and S-type glass fibres embedded in a filled

resin matrix (FibreKor Post).

➢ Fibre-reinforced composite posts consist of a resin matrix, in which structural reinforcing

carbon fibres or quartz/glass fibres are embedded.

➢ Black carbon fibre-reinforced composite posts are, on the one hand, poorly suited for

combination with translucent full ceramic restorations due to their unfavourable optical

properties. On the other hand, carbon fibre posts also have unfavourable biomechanical

properties.7


34

CLINICAL APPLICATIONS IN PROSTHODONTICS

• The main application of FRCs in dentistry is related to provisional or definitive prosthodontics.

By using FRCs, FDPs and veneers can be realized in a minimal invasive fashion, utilizing

combinations of various kinds of adhering and retentive elements.

• A resin bonded FRC prosthesis may contain inlays/onlays, surface bonding wings, and

crowns. Direct and indirect frameworks can be made also immediately after extraction of tooth

[Cramer et al., 2011].

• FRC FDPs could be fabricated as surface-retained, inlay-retained, or full coverage crown

retained prostheses.

• The fabrication could be realized directly in the mouth or can include prefabricated pontics,

simplifying the fabrication technique and providing more predictable outcomes.

The results of mechanical and adhesion properties of FRC frameworks appear to be

encouraging. In addition, FRCs can be used in the repair of existing conventional prosthetic

devices. Repairs of veneers of porcelain-fused-to-metal restorations with resin composite veneers

can be made using woven glass fiber reinforcement, thus increasing the strength of the repair. In

addition, removable devices could be reinforced using FRCs. Finally, FRCs can be used in indirect

pontic fabrication, also in combination with CAD/CAM based technologies.7

Conservative treatment of missing tooth replacement:

• Chair side tooth replacement is an excellent application for fibre reinforcement composite

technology. 2

• Previous attempts at chair side tooth replacement involved the use of pontics derived from

extracted teeth, acrylic resin denture teeth with or without lingual wire reinforcement, and resin

composite.

• These were attached to abutment teeth with acid-etched bonded particulate composite. The

abutment teeth used for these approaches were usually not prepared; most often, tooth

replacement was only for the anterior region and the procedure was considered a short-term

solution.


35

• The chair side fibre reinforced composite prosthesis offers a fast, minimally invasive approach

for tooth replacement that combines all of the benefits of the fibre reinforced composite

material for an esthetic, functional, and potentially durable result.

• A denture tooth or a natural tooth (in the case of an extraction of a periodontally involved

incisor) can be used as the pontic.

Selection criteria for this tooth replacement approach include:

1. A patient who desires an immediate, minimally invasive approach

2. A patient who requires an extraction in an esthetic area and desires an immediate replacement

3. Abutment teeth with a questionable long term prognosis

4. Anterior disarticulation during mandibular protrusive movements

5. A non-bruxing patient

6. Cost considerations 2

Repair of Acrylic Resin Prosthesis

• Both unidirectional and woven light-polymerized FRC strips can be used effectively for chair

side repairs of fractured acrylic resin prostheses. As mentioned earlier, FibreKor (Jeneric/

Pentron) and Vectris (Ivoclar/ Williams) are unidirectional materials available for laboratory

use.

• Splint-It (Jeneric/Pentron), another chairside material, is available either as a unidirectional or

a woven fibre. All of these materials have significantly greater flexural properties than

unreinforced resin.

• Woven FRC has a shorter memory than unidirectional FRC, which makes it easier to handle;

however, unidirectional FRC has superior flexural properties and will likely provide a stronger

repair.


36

Indications for Chair side Repairs with Light-polymerized FRC

Virtually any acrylic resin prosthesis or appliance can be repaired with light-polymerized FRC:

1. Complete dentures

2. Acrylic bases of partial dentures

3. Provisional removable partial dentures

4. Provisional FPDs

5. Obturators

6. Palatal lift appliances

7. Orthodontic retainers

8. Occlusal splints and night guards4

CLINICAL APPLICATIONS IN PERIODONTOLOGY

➢ Periodontal or posttraumatic FRC splints have been reported in clinical periodontology. Splints

are used to stabilize teeth, which have become loose as a result of supporting bone loss as a

consequence of periodontal disease.

➢ The main advantage of stabilization splints is the reduction of tooth mobility. FRC periodontal

or posttraumatic splints have been reported to have reliable long term stability.

➢ In fact, fiber reinforced frameworks showed higher flexural forces when compared with

conventional metallic wires.

➢ Moreover, FRC splints showed high flexural resistance also when polymerized directly with

polymerization lamp without laboratory oven post polymerization, thus reducing the number

of clinical steps and number of appointments for the patients.

➢ The common failure types are debonding and fractures. In fact, the splinting with FRC

materials of periodontally compromised teeth that have different mobility grade is prone to

debonding, with the mobility grade as main causative factor.

➢ However, FRC splints can be easily repaired, so in many cases it is not necessary to completely

debond the framework with the substitution with a new one.7


37

Tooth Stabilization and Splints:

➢ Fibre reinforced composite materials are an excellent choice for the stabilization of mobile

teeth due to periodontal reason or due to any trauma.

➢ Chair side-fabricated fixed splints have previously been made from material combinations that

have included resin composites, wire, wire mesh, wire embedded in amalgam and resin and

fibre mesh embedded in composite.

➢ All of these materials suffered from various problems like Poor handling characteristics, Over

bulking ,Insufficient bonding of the internal structural materials to the dental resins, Poor

esthetic outcome, Fibre splints overcome these drawbacks and provide ease in tooth splinting.

Splinting can be done on palatal/lingual surfaces, labial surface or both the surfaces.4

CLINICAL APPLICATIONS IN ORTHODONTICS

➢ The main use of FRCs in clinical orthodontics is as fixed retention. After orthodontic treatment,

the need for maintaining the teeth in correct position is crucial for long term stability of clinical

results.

➢ These bonded retainers appear to be both relatively independent of patient cooperation and

well accepted by patients.

➢ Bond strength is reported to be sufficient both on enamel and on dentin. Clinical reliability is

also reported to be successful for moderate time.

➢ A great advantage of FRC splints over conventional metallic retention is aesthetics. Fibers are

barely invisible and do not affect the translucency of teeth [Karaman et al., 2002]. This aspect

is important, considering the higher number of adult patients who request an orthodontic

therapy.

➢ Finally, FRCs are metal-free and are indicated for adult and young patients screened by

Nuclear Magnetic Resonance or in subjects allergic to metals. On the other hand, FRC splints

are more rigid than conventional metallic splints, thus leading to a higher ankyloses risk of

teeth involved.


38

➢ However, the application of FRC with a spot-bonding technique has been proposed, in order

to reduce framework rigidity, thus allowing physiologic tooth movement.

➢ Clinical success of FRC resins has been reported also for space maintainer purpose. The early

loss of deciduous molars is a frequently encountered problem in dentistry and, if untreated, it

could evolve in various orthodontic problems. Space maintainers are developed to prevent the

loss of the space.

➢ FRC space maintainers can be prepared on plaster models of patients and fixed directly to the

adjacent teeth. In addition to stabilization uses, in orthodontics, FRCs have been proposed also

for active tooth movement. 4

➢ Groups of two or more teeth can be splinted with FRCs and moved “en masse” with sectional

mechanics. One other application of FRCs has been proposed as innovative materials for

fabrication of brackets and wires; yet only a few research papers have been conducted on the

topic.

Applications of fibre reinforced composite in orthodontic practice

1. Fixed orthodontic retention appliance

2. Fixed space maintainer

3. Temporary esthetic retention appliance

4. Posttraumatic stabilization splint 7


39

CLINICAL APPLICATIONS IN ORAL AND

MAXILLOFACIAL SURGERY

➢ The use of FRCs has been recently reported also in oral and maxillofacial surgery. These

materials can be applied in oral implantology for bone replacing and bone anchoring

implants.

➢ The rationale for this application is that, although metal implants have successfully been

used for decades, devices made out of metals do not meet all clinical requirements.

➢ Metal objects may interfere with some medical imaging systems, while their stiffness also

differs from natural bone and may cause stress shielding and overloading of bone.

➢ Glass fibers are responsible for the load-bearing capacity of the implant, while the

dissolution of bioactive glass particles supports bone bonding and provides antimicrobial

properties for the implant.

➢ Moreover, FRCs materials can be used in maxillofacial discipline for orbital floor implants,

cranioplasty implants, and craniofacial bone reconstruction.7


40

CLINICAL APPLICATIONS IN PAEDIATRIC

DENTISTRY

➢ In paediatric dentistry FRCs can be used in almost all the fields as described above:

restorations, space maintainers, splints, or other frameworks. The main difference is that

the enamel of primary teeth is significantly different compared to permanent enamel.

➢ The differences have been mainly detected in composition, mechanical characteristics,

bond strength, and clinical performance. However, the FRC devices used in paediatric

dentistry showed acceptable clinical performance, durability, and ease of use.7

CLINICAL USE OF DENTAL FRCS AS FILLING RESIN

COMPOSITES (POSTERIOR BULK FILLING

MATERIAL)

➢ Although amalgam has shown its many benefits as dental restorative material its use is

ending due to environmental reasons. Direct resin composite restorations are used used

for the treatment of damaged tooth structure allowing high cost-effect ratio for the

treatment outcome.

➢ Particulate filler resin composites have fulfilled direct application requirements in terms

of material cost but often failed in terms of longevity of restorations made by general

practitioners.

➢ One reason for the limited longevity of restorations is low mechanical strength of the

particulate filler resin composite as material and inadequately adjusted occlusion, which

can cause high local stress concentrations and damage the restoration.

➢ Resin composite restorations and ceramic restorations do not become adjusted to the

occlusion like amalgam restorations did during long lasting setting reaction. Occlusal


41

adjustments of the resin composite and ceramic restorations must be made by the dentist

with high precision.

➢ Utilization of reinforcing fibers in filling composites to toughen the material has been

tested for years but not until recently, the reinforcing effect by fibers has been proved.

➢ Reasons for the poor success of previous FRC filling materials have been of selecting of

too short discontinuous fibers, which were not even in theory able to increase strength

and toughness of the resin composite.

➢ The current concept of using FRC in fillings is based on the bilayered composite system

in which FRC base is made of discontinous fibers with length of the fibers exceeding the

critical fiber length in the dimethacrylate polymer matrix.

➢ Fibers in the FRC increase toughness and other physical properties of the material

compared to regular filling composites.

The function of the FRC base for filling composites is to provide a crack propagation

prevention layer for the restoration. The occlusal surface of the FRC is covered with more

polishable and wear resistant particulate filler resin composite. The bilayered resin

composite structure is considered as a biomimetic restoration system by mimicking the

fibrous structure of dentin-enamel complex.8

ever X Posterior Schematic representation of biomimetic

(bilayered) posterior composite restoration.

Garoushi et al. J Invest Clin Dent. 2018.


42

➢ The failures of composite resins are due are typically due to secondary caries and bulk

fractures of the composite. These relate to the material’s properties; particulate filler

composites are prone to crack propagation and therefore have low damage tolerance,

causing bulk fractures to occur. On the other hand, particulate fillers keep the composite

isotropic in terms of its many properties, including polymerisation shrinkage.

➢ Shrinkage causes gaps between the filling and the tooth and creates a predisposition to

secondary caries. Research studies using FRCs in tooth filling applications have shown

how the structure of a restored tooth can be more biomimetic. everX Posterior is a short

fibre-reinforced composite which is used to replace tissue in damaged teeth, especially

dentine.

➢ The fibres of the everX Posterior material simulate the collagen in the dentine and provide

enhanced toughness for the restored tooth, while at the same time, the fibres also control

and minimise polymerisation shrinkage.

➢ everX Posterior is used as a bilayered filling material, i.e. the outermost part of the filling,

which simulates enamel, is made of high quality hybrid composite resin.9

(Vallittu PK. Flexural properties of acrylic polymers reinforced with unidirectional and woven

glass fibres. J Prosthet Dent 1999;81:318-326.)

A cross section of everStick glass fibers Fibers in everX posterior stop crack propagation


43

FIBER-REINFORCED COMPOSITE AS A POST AND

CORE MATERIAL IN A PEDIATRIC DENTISTRY

➢ Management of fractured teeth have always presented a challenge to the dentists. Today,

the predictability of root canal therapy states that it can retain almost indefinitely, even

very badly broken teeth.

➢ One of the widely accepted techniques involving restoration of extensively carious or

badly fractured teeth is the fabrication of a post and core, utilizing the root canal space for

anchorage.

➢ Thus far, the only materials that have been available to the dentists for thisprocedure have

been a variety of metallic alloys. Hard and unyielding, these metals haveto be cast in the

precise shape of the prepared canals and cemented into place.10

➢ Today, materials are available, which eliminate all the intermediate steps, and control is

rendered in the hands of the dentists, to fabricate on the chair, a resilient, esthetic and

bonded post and core. One such material is fiber reinforced composites (FRCs).

➢ A recently developed bondable reinforcement fiber, Ribbond, (Ribbond THM, Ribbond

Inc., Seattle, WA) is reported to be an alternative to conventional post materialsbecause

of its aesthetic qualities, mechanical properties, and the neutral color of the reinforcing

material.

➢ First introduced to the market in 1992, Ribbond consists of bondable, reinforced ultra-

high-strength polyethylene fibers.

➢ The open and lace like architecture of Ribbond allows it to adapt closely to the teeth and

dental arch. This is an advantage over prefabricated fiber posts where adaptability to root

canals is difficult.


44

➢ Apart from this feature the Ribbond can be condensed properly in the canals with little

microleakage. The application of a fiber layer increases the load bearing capacity of the

restoration and prevents crack propagation from the restoration to the tooth.

➢ When prefabricated fiber post is placed in flexure, cracks appear on the tensile face and

due to brittleness of the material rapidly propagates causing failure.10

STEPS INVOLVED IN THIS PROCEDURE ARE:

• The tooth should be adequately obturated and the canal space should be prepared.

• The use of Ribbond does not require additional tooth preparation as is required for metal

posts.

• Isolation of the tooth using rubber dam, high suction evacuation with cotton rolls.

• Gutta percha to be removed using gutta percha solvent until the desired length for the post

was achieved.

• The post hole shaped using gates glidden drills,cleaned with 5% sodium hypochlorite and

dried.

• The width of Ribbond (Ribbond THM, 2, 3 or 4 mm, Ribbond Inc., Seattle WA) is decided

on the root canal space available.

Radiograph showing post space

Source: Pic courtesy Acharya S. and Tandon S. srmjrds 2015


45

• The depth of the post space measured using a periodontal probe, and a 3mm wide Ribbond

cut using special scissors provided with the kit (Ribbond starter kit, Ribbond THM,

Seattle), measuring twice the depth of the post space and 3-4 times the height of the core

build-up and placed in dual cure adhesive resin and set aside in light protected container.

• The root canal wall etched for 15 s, washed for 30 s and then gently air-dried.

• Excess water removed from the post space using paper points (Spident, SPI Dental Mfg.

Inc., Korea).

• The dual cure adhesive resin (Ed Primer II A and B) applied using a microbrush in 2

consecutive coats and gently air-driedto evaporate the solvent.10

• Dual cure resin cement (Panavia F,Kuraray, Japan) is injected in the canal space.

• The Ribbond removed from the resin and the excess resin was removed using a hand

instrument, folded in a V-shape and coated with dual-curing resin cement (Panavia,

Kuraray MedicalInc., Japan).

• The piece of ribbon then placed in the postspace in a facial-lingual direction with an

endodontic plugger.

• Excess resin cement removed, and the cement cured for 20s.

• The two protruding ends of the Ribbond strips formed the reinforcement for the core build-

up to replace the lost coronal portion of the tooth.

• The remaining resin mix from the syringe extruded onto this framework to create a core

resembling almost like the shape of a lower central incisor.

• The space between the protruding ribbon ends was filled with resin so as not to leave any

voids.


46

• Composite resin should also be placed so as to cover the ribbond ends completely and leave

none of them exposed on the outer surface of the core.

• All the material thoroughly light cured to create a set surface.

• The material left in the mouth for a couple of hours to ensure complete set of the self curing

component of the resin mix.

• The result of this procedure came out to be a single piece post and core, which was bonded

onto the root, creating a solid structure without any wedging effect on the root. There were

no voids and resin conforming to the inside shape of the canal space ensured that the fitting

problems normally associated with cast posts were eliminated.10

• The bands of Ribbond reinforced the resin material and made it extremely strong and

durable.

• The restorative procedure completed by building up the tooth using dual cure hybrid

composite resin following technique of small progressive build up.

• If the development of occlusion is not completed a crown should be advised at a later stage

when occlusion development is complete.

In recent times the number of endodontic procedures have increased with extremely good results

and restoration of teeth after endodontic treatment is becoming an integral part of the restorative

practice in dentistry even when the teeth have gross lesion. Fibre-reinforced composites emerges

as a boon to the esthetic dentistry.


47

Fibre-reinforced composites have been used in pediatric dentistry in deciduous teeth for restoring

grossly decayed tooth structure in patients with early childhood caries where restoring function

and esthetics presents as a challenge. There are very few cases reported for permanent anterior

teeth in pediatric patients but it has been used as a post and core material in a permanent tooth for

a pediatric patient with satisfying esthetic results and improved mechanical properties.

Postspace preparation

Source: Pic courtesy Acharya S. and Tandon S. srmjrds 2015

Measured amount of Ribbond

prepared Ribbond prepared to be

inserted in the canal


48

DIRECT FIBER-REINFORCED COMPOSITE

RESTORATION IN AN ENDODONTICALLY-TREATED

MOLAR

• The reconstruction of structurally compromised non-vital posterior teeth may represent one

of the most challenging adhesive-based restorative procedures.

• Several factors may influence the longevity of direct fiber-reinforced resin composite

restorations: endodontic procedures prior to post cementation, dentin and/or post surface

treatments, selection of the appropriate post design and architecture, resin composite

polymerization and layering techniques.

• Thus, different specialties, such as endodontics and restorative dentistry, should work as a

team to improve the longevity of restorations.

• Endodontically, treated teeth are weakened because of a decrease in water content and loss

of dentin. The decay process and/or tooth fracture may be responsible for the structural

weakening of non-vital teeth; the tooth preparation required for adequate endodontic

treatment may also contribute to the increased fragility.11

• After endodontic therapy, selecting the appropriate reconstruction for each non-vital tooth

should be based on the remaining hard tooth structure, the number and thickness of the

residual cavity walls, the position of the tooth in the arch and the load implied.

• Resin bonded composite (RBC) restorations showed a strengthening effect on the tooth

structure, with fracture resistance similar to that of unaltered teeth. For many years, direct

adhesive restorations have been used for anterior teeth with conservative endodontic access

and intact marginal ridges.

• Posterior non-vital teeth with an intracoronal conservative access only have also been

restored with direct RBC.


49

• Conversely, for many years, full coverage restorations have been indicated when the teeth

are weakened by additional cavities on both the anterior and posterior area.

• With the use of improved adhesive systems in the last decade, clinicians started proposing

alternative techniques to reconstruct severely damaged teeth; the main goal of the new

build-up protocol is preservation and reinforcement of the remaining sound tooth structure.

• Although most of the coronal portion of the tooth is compromised, RBC restorations may

serve to properly build-up anterior non-vital teeth by using adequate layering and curing

techniques.

• RBC restorations are indicated in posterior teeth as long as sufficient tooth structure is

preserved; more compromised teeth with missing marginal ridges and/or cusps may require

placement of a post to gain additional retention of the core.

• Lately, prefabricated tooth-colored fiber posts have been introduced and have

demonstrated advantages over conventional metal posts.11

• Though they are esthetic, bond to tooth structure and have a modulus of elasticity similar

to dentin but prefabricated tooth-colored fiber posts require the dentin preparation to fit the

canal space, thus further weakening the remaining tooth structure.

• Prefabricated posts are indicated for round post space; whereas, custom posts are required

to closely adapt to the contours of wide root canals or oval-shaped canals.

• Lately, increasing interest has also been devoted to the use of direct Ultra High Molecular

Weight Polyethylene (UHMWPE) custom fiber reinforced post systems.

• Being that they are bondable reinforcement fibers, UHMWPE posts adapt to the shape of

the root canal; they are indicated for both round- and oval shaped canals. The risk of root

perforation is eliminated as enlargement of the root canal space is not required.


50

• The following steps are from a article which reports on the three-year longevity of direct

fiber-reinforced RBC restorations in a severely damaged, non-vital molar and discusses the

benefits of UHMWPE posts. Procedure as described in the case report has been enumerated

below with reference to the material used.11

STEPS INVOLVED IN THIS PROCEDURE ARE AS FOLLOWS:

• A rubber dam was placed and the existing temporary filling removed. A #12 and #14 coarse

ball-shaped bur was used to rounden sharp angles. No bevels were placed on the occlusal,

proximal or gingival surfaces.11

( Source: Pic courtesy Delperi S. Operative dentistry2008;33:209-214.)


• Three to four millimetres of gutta-percha were removed from the mesio-buccal root canal.

A sectional matrix was placed on the tooth and interproximal adaptation was secured using

wooden wedges.



51

• Enamel and dentin were etched for 30 seconds using 35% phosphoric acid; etchant was

removed, and the cavity was washed for 30 seconds with water spray, being careful to

maintain a moist surface.


• A fifth generation 40% filled ethanol based adhesive system was placed in the preparation,

gently air-thinned to evaporate solvent and light cured for 20 seconds at 800 mW/cm2

from the occlusal surface using an LED curing light.

• A particular composite placement technique was selected to build-up the restoration.11 The

combination of RBC wedge-shaped increments and the UHMWPE fiber-reinforcement

system was considered to be of paramount importance to further reduce polymerization

shrinkage, better support the RBC, reinforce the remaining tooth structure and reduce total

composite volume mass An UHMWPE triaxial fiber (Ribbond) was selected, and the

dental assistant started to manipulate it according to the manufacturer’s instructions.

• Triaxial fibers were wetted with an unfilled resin, excess resin was removed andthe fibers

were completely covered with a B1 light cured flowable resin composite and placed in the

central area of the restoration.

• UHMWPE triaxial fibers were folded and each end wasplaced into the root canal using a

thin composite spatula.


52

• The fiber-resin complex and flowable resin composite were light cured at 800 mW/cm2

for 120seconds to assure complete polymerization of the fiber resin composite complex

down into the canal.

(Source: Pic courtesy Delperi S. Operative dentistry2008; 33:209-214.)

• Vit-l-escence microhybrid RBC was considered the material of choice for restoring the

non-vital teeth, because of its variety of enamel shades and excellent mechanical

properties.

• In order to avoid microcrack formation on the remaining facial/palatal wall, the authors

used a previously described technique, based on a combination of pulse and a progressive

curing technique.

• The sectional matrix was burnished against the adjacent tooth. Tooth build-up was started

using 2 mm triangular-shaped (wedge-shaped) gingivo-occlusal placed layers of amber

(PA) and smoke (PS) enamel shades to reconstruct the proximal and facial surfaces.

• This uncured composite was condensed and sculptured against the cavosurface margins

and sectional matrix; each increment was pulse cured for three seconds at 800 mW/cm2 to

avoid micro-crack formation.

• Final polymerization of the PA and PS composite proximal and palatal/facial walls was

then completed at 800mW/cm2 for 20 seconds.

A piece of Ribbond fiber was wetted with unfilled resin,

covered with flowable composite and inserted into the

mesial buccal canal

The enamel contour of the tooth was built-

up using wedge shaped increments of PA

and PS shades


53


• The enamel contour of the restoration was built-up, offering more reference to creating the

correct occlusal anatomy.11

• Dentin stratification of the facial, palatal and proximal walls was initiated, placing 2 mm

wedge-shaped increments of A3 RBC into each enamel wall, avoiding contact with fresh

increments.

• Successive A4 and A3.5 increments were placed in the central area of the restoration

surrounding the resin impregnated fiber composite system to increase the chroma,

unnaturally reduced by previously using B1 flowable composite.

• Each dentin increment was cured using a progressive “curing through” technique(40

seconds at 800mW/cm2 through the facial and lingual walls instead of a conventional

continuous irradiation mode of 20 seconds at 800mW/cm2 from the occlusal surface).

• At this point, the middle third of the dentin restoration was built-up using a combination

of A2 and A1 resin composite. Enamel layers of PF or PN were applied to the final contour

of the occlusal surface according to a successive cusp buildup technique.

• This final layer was pulse-cured for one second at 800 mW/cm2. A waiting period of three

minutes was observed to allow for stress relief; the wedges and matrix were removed, along

Dentin stratification was performed

placing A4 to A1 shades

The restoration was completed with

the application of

PF/PN shade to the final contour of

the occlusal surface


54

with the rubber dam; occlusion was checked and the restoration was finished using the

Ultradent Composite Finishing Kit.

• The final polymerization cycle was completed by irradiating the restored tooth through the

facial, palatal and occlusal surface, respectively, for 20 seconds at 800mW/cm2.

• Final polishing was performed using Jiffy polishing cups and points (Finale, Ultradent).11

The reconstruction of severely damaged non-vital teeth requires knowledge of both curing and

adhesive techniques. Fiber-reinforced resin composite restorations allow for the utilization of

conservative tooth preparation, preservation and reinforcement of sound tooth structure. Selection

of the appropriate fiber-post design and architecture is paramount to achieving this goal.

The rigidity of traditional metal posts and novel ceramic posts is a major concern, because

the rigidity may pose a risk of root fracture (Torbjörner et al 1996, Schmitter et al. 2007). A stiff

post transmits the occlusal forces to the surrounding dentin. Tension stress at the apical regions of

the post cause microscopic fatigue fractures, which, with time, may lead to macroscopic fractures

of the root.

➢ There are two ways of reducing the tension stress that causes fatigue fracture of the root.

➢ The traditional approach is prolonging the post preparation of a stiff post. This principle,

which is called the moment compensation principle, is in practice, very difficult and not

always possible to carry out.

➢ Another current approach, called the modulus compensation principle, is to use a post

material which is biomechanically more suitable, e.g. a post material which is strong

enough but also flexible so that it can behave like tooth structure inside the root under the

occlusal forces.

➢ The flexibility or stiffness of a material may be described by the so-called modulus of

elasticity or elastic modulus (Young’s modulus, E-modulus).


55

➢ The E-modulus is the constant that relates the stress and the strain in the linear elastic

region where elastic deformation of a material occurs (Gutmann 1992, Van Noort 2002).

A group of materials which offers stiffness equal to that of dentin, as well as high durability

is the group of fibre-reinforced composites (FRC).11

FIBER REINFORCED COMPOSITE- FIXED FUNCTIONAL SPACE MAINTAINERS

➢ Premature loss of the primary teeth is a common occurrence in children. A space maintainer

is the safest and effective method in preventing malocclusions pertaining to early loss of a

primary tooth and is durable and economical.

➢ Among the various space maintainers used in pediatric dentistry, band and loop is the most

commonly used fixed space maintainer.

➢ However, the construction of band and loop requires three steps, it involves a clinician as

well as a laboratory technician, and therefore it is expensive.

➢ With the advances in the technology and materials, there is a need to search for an

alternative to overcome various disadvantages of the band and loop space maintainer.

➢ Fiber-reinforced composite resin (FRCR) provides new opportunities to us in this regard.

In addition to their mechanical properties, FRCR materials are now being used in many

areas of dentistry due to their advantages, such as the possibility to be prepared by the

dentist chairside, the number of visits are decreased, adherence to teeth structures by way

of adhesive applications along with improved aesthetic properties.

➢ Fabrication of SMs with fiber reinforced composite (FRC) possesses the advantages of

being easily manipulated and directly chair-side applied. Moreover, they are fixed,

minimally invasive, aesthetic, readily repaired, reversible, biocompatible, and of relatively

lower treatment costs. However, their longevity is still a controversial issue.


56

➢ Polyethylene fiber-reinforced composite used as a fixed space maintainer offers many

advantages. FRC has an aesthetic appearance, is easily manipulated, can be quickly

inserted in a single-visit procedure that requires no laboratory services, poses no risk of

damage to abutment teeth and is easy to clean.

There are various designs and methods by which a space maintainer can be fabricated. They

are as follows:

DESIGN 1: (CHAIR SIDE FABRICATION)

STEPS INVOLVED IN THE FABRICATION OF FRC SPACE MAINTAINER ARE AS

FOLLOWS:

• Fabrication of a space maintainer resting on the buccal surfaces of the neighboring teeth.

• Maxillary and mandibular impressions are obtained with alginate and models have been

obtained.

• Space spans on the models measured and recorded.

• Glass fiber material has been cut in required size and has been shaped on the model of each

patient in accordance with the directions of the manufacturing company.

The following procedures to be carried out on abutment teeth:

• Abutment teeth cleaned with non fluoride polishing paste.

• Isolation precautions are taken.

• Etching done with 37% phosphoric acid for 30 seconds (15 seconds for permanent teeth).

• Bonding agent (Prime & Bond NT; Dentsply International Inc., Milford, DE, USA) applied

and scrubbed for 20 seconds and 10 seconds light applied for polymerization.

• Flowable composite (Flow Line; Heraeus Kulzer, Dormagen, Germany) applied to enamel

surfaces.12

• Space maintainers that previously prepared are placed and then polymerized by applying light

for 20 seconds. Here a halogen light device (Blue Swan; Dentanet, Ankara/Turkey) with light

power of 800 mW/cm2 is used during the polymerization of both the bonding agent and the

composite resin material.

• Polishing and final occlusion controls made.12


57

(Source: Pic courtesy Tayab T and Srinivasan I.Dental Traumatology2011;27:159-162.)

STEPS IN THE FABRICATION:

• The initial framework of FRC loop is constructed using a commercially available

polyethylene fiber system (Ribbond, Inc., Seattle, WA, USA).

• Ribbond fiber of 40 mm length and 2 mm in breadth is wetted with unfilled adhesive resin

(Adper™, Single Bond, 3M-ESPE, St. Paul, MN, USA) to formulate the loop, leaving 5

mm of fiber on each end for attachment to the abutment tooth13

2mm Ribbond fiber being utilized Ribbond being wetted with adhesive resin

(Source: Pic courtesy Yeluri R and Munshi AK. Contemp Clin Dent 2012;3:S1:26-8.)


58

• A thin layer of restorative composite resin is added to the outer portion of the fiber, leaving

5 mm of the fiber on each end to provide initial rigidity, handling and adaptability to the

unetched middle third of the buccal and lingual surface of the mounted molar tooth in

acrylic as shown in the figure below.


• The assembly is then light cured for 40 seconds through its entire length. The loop is then

detached from the tooth; restorative composite resin is added to the inner portion of the

loop except the 5 mm of the fiber on each end and light cured for 40 seconds. The loop is

then finished and polished with finishing burs and soflex discs.13


• The buccal and lingual surfaces of the tooth are etched with phosphoric acid for 15 s,

rinsed with water, dried, and bonding agent is applied and cured for 40 seconds.

Mounted teeth in acrylic to simulate the space

Wetted ribbond fiber being

manipulated to form a loop

FRC LOOP AFTER FINISHING

AND POLISHING


59

• The loop is finally attached to the tooth using restorative composite resin followed by

finishing and polishing.13


Causes of failure of Fiber reinforced composite space maintainer:

➢ Debonding of fiber-composite interface

➢ Debonding of enamel-composite interface

➢ Fiber frame fracture

➢ Caries or gingival inflammation

CLINICAL SUCCESS OF FRC AS A SPACE MAINTAINER:

• Space maintainers made from FRCR material which are adhered to the surfaces of teeth

have various advantages, such as biocompatibility, esthetics, ease of application, and fast

preparation by the dentist or assistant in one appointment.

• The stabilization of abutment teeth via space maintainers in developing jaws is seen as one

of the disadvantages of the method; however, the flexible nature of the fiber material

decreases this effect.

• The FRCR space maintainers were fixed on primary teeth–primary teeth or primary teeth–

permanent teeth.

FRC LOOP AFTER FINISHING AND POLISHING


60

• When such space maintainers are fixed on primary teeth, the prismless enamel surface

structure of primary teeth may have negative effects on the retention of resin material.

• It has been stated in previous studies that space maintainers prepared similarly using fiber

material are more stable when fixed on permanent teeth.

• Swaine and Wright have carried out a study during which they determined the failure rate

as 18% in cases when primary teeth are used as abutment and as 60% in cases when

application is made between primary and permanent teeth.

• Researchers think this is due to isolation problems in addition to the fact that

polymerization light cannot reach the back region sufficiently.

• Researchers have suggested etching at the area to where space maintainers will be applied

to decrease the external prismless layer of the enamel.14

• The failure rate of wire-composite space maintainers during the first 6 months varies

between 4 and 30%, whereas the failure rate at the end of the first 6 months in our study is

2.3%, which is quite low.

• Studies during which the retention of FRCR space maintainers was compared for 12

months with those of band-loop space maintainers have indicated the success ratios as 53

and 33% respectively.

• Baroni et al. emphasize that occlusal stresses are more important for the long-term use of

space maintainers instead of their design. Furthermore, in another study made by Kara et

al. to compare the biomechanics of space maintainers, it is found that load distributions of

band-loop, direct bonded, and fiber-reinforced space maintainers seem comparable.

• It has also been put forth that children mostly use the right side of the jaw when chewing

and hence, space maintainers fixed to the right side of the jaw experience more occlusal

stress and are thereby lost earlier.


61

• Kirzioğlu and Ertürkhave stated that the FRC space maintainers they placed to the right

side of the arc are less successful in comparison with those placed to the left side.

• It has been determined during the study carried out by Subramaniam et al. that 46% of

the space maintainers applied to the right side of the jaws are unsuccessful.

• On the contrary, Santos et al. have determined a high failure rate in the left maxilla region,

whereas Kirzioğlu and Yilmaz,Baroni et al. have determined no statistically significant

difference during their studies in which they compared wire-composite space maintainers

placed to the right and left sides of the jaw.14

• Studies in the literature carried out in this topic are generally in the form of either a case

report or the evaluation of a method. The number of studies examining the long-term

success of such space maintainers is rare.

ANTERIOR FIBER-REINFORCED RIBBON COMPOSITE RESIN BRIDGE:

• Different therapeutic options can be considered for the replacement of a congenitally or

traumatically missing permanent incisor in young children and adolescents. One of the

greatest challenges that the dentist faces is the esthetic and functional rehabilitation of a

missing anterior tooth.

• The procedure becomes difficult when the missing tooth cannot be replaced by an implant-

supported prosthesis or a conventional fixed dental prosthesis due to a local bony defect,

inadequate volume of bone in the edentulous area, occlusal function, systemic disorders,

or the socioeconomic status or unwillingness of the patient to experience invasive implant

surgery or the preparation of natural teeth for retainers.

• The fiber reinforced composite resin FPD (FRC FPD) can be considered a viable

alternative in such situations or in those in which conservative preparation is needed.


62

CLINICAL PROCEDURE:

• After oral prophylaxis and restoration of cervical caries of the maxillary left central incisor

with light cure composite resin, a preliminary maxillary impression is made with polyvinyl

siloxane elastomer of putty consistency.

• The composite resin pontic is fabricated using an incremental buildup technique on the

impression of the maxillary left central incisor) followed by light curing.

• The pontic obtained by this technique replicates the maxillary left central incisor which is

made to resemble the maxillary right incisor with minor modifications using composite

resin.15

• A properly finished and polished modified ridge lap pontic design is made.

• After fabrication of the pontic,the same impression is poured with die stone to obtain a

cast.

• The pontic is then placed on the cast in accurate buccolingual, mesiodistal, and

cervicoincisal position as per the esthetics and stabilized with wax from the palatal side.

• A putty matrix/index is then made with polyvinyl siloxane elastomeric putty on the cast

with the pontic in position.

• This matrix is used for accurate positioning of the pontic in the patient’s mouth and it helps

to minimize the pressure exerted by the pontic on the edentulous area.

(Source: Pic courtesy Singh K et al. Case reports in dentistry.2014.)

Putty index fabricated on cast after stabilization of pontic, Fiber reinforced composite resin placed

on cast with wax slots after stabilization of pontic with putty


63

• Palatal grooves, approximately 3mm wide and 1.5mm deep, involving at least three-

quarters of the mesiodistal width of the abutments, were prepared with round and inverted

cone diamond rotary burs, in the patient’s mouth.15


• A similar size groove involving the whole of mesiodistal width of the pontic was prepared

on the pontic.

• The grooves prepared on abutments and pontic should be at the same level.The distance

between the grooves was measured and a piece of the fiber ribbon (Perfect Splint, Hager

Werken, Germany) is cut with the same dimensions as the space between two grooves.

• The bonding agent is applied on the cut piece of fiber ribbon and kept aside.

• The fiber impregnated with bonding agent should be kept out of the dental light until used.

• One should avoid touching the fiber ribbon after it is wetted with bonding agent via the

fingers, because any contact can contaminate its reactive surface layer.

• The prepared slots and mesioproximal surfaces of both the abutments were then etched

with 37% phosphoric acid for 15 seconds.

• After thoroughly rinsing and drying, a bonding agent was applied with amicrobrush

applicator on both the prepared abutment areas and on the groove on the pontic.

• Excess bonding agent was removed with the brush tip and by gently blowing with air. The

bonding agent was light cured for 15 seconds.15

• The pontic was then placed in the patient’s mouth and held in accurate position with the

putty index.

Slots prepared at palatal surface of abutments


64


• Composite of the selected shade is first placed properly in the grooves on the abutments

and on the pontic followed by placement of the cut piece of fiber ribbon along the grooves

using composite placement instruments.

• The excess composite which flows into the proximal embrasures should be removed

carefully before starting polymerization.

• The composite with fiber ribbon is carefully polymerized with a Quartz tungsten halogen

light curing unit for 40 seconds each from the buccal and palatal surfaces of both abutments

and from the lingual surfaces of pontic.

• Finally a flowable composite is placed over polyethylene fibers, giving a smooth, glossy

appearance on palatal surfaces. Occlusion is evaluated and premature contact eliminated.

Figures below show incisal and labial views of definitive prosthesis, respectively.15

INCISAL VIEW OF DEFINITIVE PROSTHESIS LABIAL VIEW OF DEFINITIVE PROSTHESIS


Fiber reinforced composite resin placed in slots after stabilization of pontic with putty index.


65

• Fiber reinforced composite resin FPD and resin bonded FPD can be considered

conservative approaches for replacing missing anterior tooth in certain favorable clinical

conditions.

• A common problem with metal ceramic resin bonded FPD has been the grayish

discoloration of the incisal third of the abutment teeth and debonding of metal retainers

from tooth.

• The fiber reinforced composite resin FPD require only preparation of palatal slots on the

middle of the palatal/lingual surface.

• The retention of these FPD depends on the proper placement of fiber framework in the

grooves and careful bonding procedure.

• The incidences of debonding are less when fiber framework is properly placed in the

grooves and bonding procedure is carefully executed.

• In addition to above-mentioned advantages, other advantages include completion of

procedure in single appointment, low cost, and less invasiveness, and repairs can be

carried out directly without the need for any complicated techniques or materials.

• Adjustments to the design, esthetic details and occlusal relationships may be preparation,

advancement in bonding systems, and reported success suggest that this prosthesis can be

used as a long term definitive treatment alternative as in the case report described above.

• Long term success depends on proper abutment selection, slot preparation, careful

bonding technique, and type of occlusion.15

• There should be no contact on the pontic, sufficient horizontal overlap, and minimum

vertical overlap.

• This technique is simple, easy, and less time consuming than other approaches.

• It is an affordable and quick solution for the patients who reject more invasive

treatments.15


66

USE OF FRC IN DENTAL TRAUMA:

➢ FRCs can be used for splinting in case of trauma to primary or permanent teeth.

➢ Clinical steps in splinting are as follows:

• The labial surfaces of the teeth to be etched, rinsed and dried, and Single Bond applied.

• To insure semi-rigidity, the interproximal region is not etched or bonded.

• After applying a flowable composite to the enamel surfaces, the Ribbond is pressed through

thecomposite against the teeth and cured.

• The Ribbond is then coated with additional flowablecomposite and cured again for 20 s.17

(Source: Pic courtesy Tuloglu N, Bayeak S and Tunc E. European journal of dentistry2009;3.)

• Two weeks later, the Ribbond splint at the interproximals is cut with a diamond bur. Then,

the splint is removed from the abutment by sliding a scalpel blade between the Ribbond

and the teeth on the most distal end.

• The remaining adhesive is then removed with a tungsten carbide bur (KometH284;

Brasseler Co., Lemgo, Germany) in a lowspeedhandpiece under coolant water and surfaces

are polished with disks.17

(A). Frontal view after stabilization with a Ribbond-composite splint.

(B). Frontal view after healing.


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FABRICATION OF CHAIRSIDE FIBER-REINFORCEDCOMPOSITE RESIN

PROVISIONAL FIXED PARTIAL DENTURES:

INDICATIONS FOR FRC FPD:

1. Optimal esthetic result

2. Metal free prosthesis is required

3. Decrease wear to opposing tooth

4. Use of an adhesive luting technique

CONTRAINDICATIONS OF FRC FPD:

1.Inability to maintain fluid control

2.Long span needed

3.Patients with parafunctional habits

4.Opposing unglazed porcelain

• First, an accurate impression of the edentulous region is made with alginate. It is usually

unnecessary to make a full-arch impression because the opposing cast is not needed.

• A stone master cast is made from the impression and used to establish the tooth contours

and tooth position according to the clinical situation.

• The stone cast is also used for the fabrication of a wax crown substitute for the edentulous

space.

• A template is constructed by loading polyvinyl siloxane into a syringe and applying it

around the wax tooth substitute on the master cast.

• A transparent template is essential because the clear matrix allows the light to reach the

resin to initiate polymerization.16

• After polymerization is completed, the template is separated from the cast by carefully

excising the occlusal aspect with a surgical knife and removing the wax crown.

• Then, the template is ready for transfer to the patient’s mouth.16


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(Source: Pic courtesy Ballo A and Vallittu PK. The International journal of prosthodontics 2011;24.)


• Next, the necessary cavities were prepared by either removing old fillings or preparing new

cavities.

• The template is transferred to the patient’s mouth and positioned correctly.

• Glass ever- Stick fibers (Stick Tech) should extend from one end of the cavity to the other.

• This length can be determined by directly measuring the span with a metal foil cord. Next,

the prepared cavities are etched, and dentin adhesive is spread throughout the bonding area.

A stone master cast (beige) was prepared from an

alginate impression, and a wax crown (blue) was

prepared to fill

the edentulous space in the stone cast.

Transparent polyvinyl siloxane was

applied with syringe

The polyvinyl siloxane template reached its final

hardnessalong the occlusal aspect, and the wax crown was

remove within 5 minutes of initial mixing.

The hardened template was separated from the

stonecast by cutting


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• A thin layer of flowable composite resin is applied, and the fiber bundle is pressed into

place and light cured for 10 seconds.

• The pontic construction was initiated by laying down a thin layer of enamel for the

underlying wall. Then, a deposition area of the template was built up.

• Next, a reinforced dentin core was constructed between the fibers. The pontic was then

coated with enamel and the template was removed.

• Finally, the pontic was finished and polished.16

(Source: Pic courtesy Ballo A and Vallittu PK. The International journal of pro sthodontics 2011;24.)


Template positioned in the patient’s mouth The enamel was etched and me foil was used to

measure the length of the fiber sticks of the sticks

A bonding agent and flowable composite resin was applied

Fiber pressed into place with hand instruments

The fibers were light cured Occlusal framework in place view showing the FRC


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FIXED PARTIAL DENTURE WITH A NATURAL TOOTH PONTIC:

• Following clinical and radiographic examinations, a fixed partial denture reinforced with

Ribbond using the natural tooth as a pontic is fabricated.

• The root of the tooth is removed below the cemento-enamel junction, and the coronal pulp

chamber is cleaned and filled with a light-cured composite resin.

• The lingual surface of the crown is trimmed and polished.17 Following completion of etching

and bonding procedures, a thin layer of flowable composite resin is applied (without curing)

to the lingual and interproximal surfaces of the abutment teeth, a length of 2-mm-wide.

• Ribbond is placed on the lingual surface of the teeth, and slight pressure is applied with a

hand instrument to create close contact at the interproximal area.(Figure:B)

• The excess resin composite is removed, and the Ribbond is light-cured for 20s. The lingual

surface of the pontic was then prepared for bonding.

• A thin layer of flowable composite was applied to the natural tooth pontic, which was placed

in the desired position on the Ribbond and cured for 20s.

• The patient’s occlusion is checked for premature contacts, and the resin composite is polished

using a polishing disc.17

Palatal View Of Polyethylenefiber-Reinforced

Composite Fixed Partial Denture

Preoperative View


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(Source: Pic courtesy Tuloglu N, Bayeak S and Tunc E. European journal of dentistry2009;3.)

➢ From clinical point of view, there is a lack of long term clinical research of FRC prostheses.

However, the longitudinal studies reported general failure rates between 5% and 16% over

periods up to 4-5 years.

➢ These finding were demonstrated for prostheses with both extracoronal and intracoronal

retainer designs, but only for patients who did not exhibit severe parafunctional habits. Van

Heumen et al. showed a survival rate of 64% after 5 years follow-up of 3-unit anterior

FRC prostheses made with the materials and techniques used in late 1990s.

➢ One study reported a much higher failure rate of 40% over a 3-year period. The recent

clinical data, on the semi-IPN resin matrix FRC FPDs made directly in patients mouth,

suggest high survival percentages (>96% at five years), which reflects material

development and learning of fabricating FRC FPDs.17

TOOTH STABILIZATION AND SPLINTS

• For the stabilization of hypermobile teethFRC materials are an excellent choice.

• Chairside-fabricated fixed splints have previously been made from material combinations

that have included resin composites, wire, wire mesh, wire embedded in amalgam and resin

and fiber mesh embedded in composite.

• All of these materials suffered from various problems: poor handling characteristics,

overbulking, insufficient bonding of the internal structural materials to the dental resins,

and poor esthetic outcome.

Polyethylene fiber-reinforced Composite fixed partial denture constructed with a natural

tooth following anterior tooth trauma


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• FRC stabilization can be either intracoronal or extracoronal, depending on the clinical

situation.

• The intracoronal technique requires a prepared horizontal channel that will accommodate

the width and thickness of the FRC reinforcement material.

• The dimensions of this channel usually range from 2.0 to 3.0mm wide and from 1.0 to

2.0mm deep. This channel is prepared in the middle to incisal third of the teeth.

• Mandibular splints are usually placed on the lingual surfaces, while a maxillary splint can

be placed on either the lingual or facial surface, depending on the occlusal relationships

between the teeth.

• The facial approach has the advantage of maintaining the occlusal stops on sound tooth

structure, preventing the restorative (particulate) composite from interfering with function.

• Intracoronal splints for posterior teeth require channels that are usually placed on the

occlusal surface; the channel can be prepared into an existing restoration and then inserted

into particulate composite, which is placed within the channel preparation.2

• FRC materials are available with different fiber architectures.

• Fiber architecture has a significant impact on both mechanical properties and handling

characteristics.

• Woven fiber is less technique-sensitive and easier to manipulate because it has less memory

than unidirectional fiber and is thebest choice for rotated or malpositioned teeth.

Unidirectional fiber has greater flexure strength and rigidity and is the better choice for

high stress situations.

• Currently, two categories of fiber reinforcement material can be used for intraoral use:

pre-impregnated and non–pre-impregnated.

Resin Pre-impregnated FRC Splinting Technique

• Pre-impregnated material (Splint-It, Jeneric/Pentron) has two fiber designs: a 2-mm woven

fiber and a 3-mm unidirectional fiber.2


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Materials required for the intraoral(chairside) fabrication of a periodontal splint are as

follows:

• Diagnostic cast

• Rubber dam

• Wedges, Stimudents, high-viscosity polyvinyl siloxane impression material

• High-speed handpiece and burs

• Phosphoric acid gel etchant

• Fourth-generation (multiple bottle) or fifth generation (single bottle) enamel-dentin

bonding agent

• Intraoral FRC material (Splint-It, Jeneric/Pentron)

• Visible light–curing flowable particulate composite resin

• Visible light–curing unit2

EXTRACORONAL SPLINTING TECHNIQUE USING PRE-IMPREGNATED FRC

MATERIAL

NON-PRE-IMPREGNATED FRC SPLINTING TECHNIQUE

• Non—pre-impregnated materials include plasma-treated, woven, polyethylene ribbons

(Ribbond Reinforcement Ribbon, Ribbond; Connect, Kerr) and flexible white continuous

filament glass ceramic fiber that has been etched and silanated (GlasSpan, GlasSpan)

Plasma treatment of the polyethylene ribbon permits a chemical union to take place

between the resin and the polyethylene fibers.

• Etching and silanation of the glass allow for both a mechanical and a chemical union of the

fibers.

• The Ribbond Reinforcement Ribbon is available in a 1.0-mm width for orthodontic

stabilization and 2.0-, 3.0-, and 4.0-mm widths for tooth stabilization and tooth

replacement.

• Connect is available in 2.0- and 3.0-mm widths. GlasSpan is available in 1.0-, 1.5 and 2.0-

mm-wide braided ropes and a 2.0-mm-wide woven tape.

• The materials used for this chairside procedure are the same as for the pre-impregnated

FRC splinting technique with the exception of the type of FRC material that is used.


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Fabrication of a periodontal splint with non–pre-impregnated FRC material

(Source: Martin A. Freilich, Jonathan C.Meiers, Jacqueline P.Duncan, A.JonGoldberg. Fiber

Reinforced Composites In Clinical Dentistry.U.S.A:Quintessence Publishing Co,Inc;2000.)

Preoperative facial view of

mandibular anterior teeth requiring stabilization

Preoperative lingual view of mandibular anterior teeth.

Lingual view of completed leno-weave

polyethylene ribbon intracoronal splint

Facial view of completed leno-weave

polyethylene ribbon intra- splint giving a very

esthetic and imperceptible result


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CHAIRSIDE CONSERVATIVE TOOTH REPLACEMENT:

• Chairside tooth replacement is an excellent application for FRC technology. Previous

attempts at chairside tooth replacement involved the use of pontics derived from extracted

teeth, acrylic resin denture teeth with or without lingual wire reinforcement and resin

composite.

• These were attached to abutment teeth with acid-etched bonded particulate composite,

acid-etched particulate composite, and either wire designs or plasma-treated, polyethylene

fiber ribbon.

• The abutment teeth used for these approaches were usually not prepared; most often, tooth

replacement was only for the anterior region and the procedure was considered a short-

term solution.2

• The chairside FRC prosthesis offers a fast, minimally invasive approach for tooth

replacement that combines all of the benefits of the FRC material for an esthetic,

functional, and potentially durable result.

• A denture tooth or a natural tooth (in the case of an extraction of a periodontally involved

incisor) can be used as the pontic.

Selection criteria for this tooth replacement approach include:

A patient who desires an immediate, minimally invasive approach

• A patient who requires an extraction in an esthetic area and desires an immediate replacement

• Abutment teeth with a questionable long term prognosis

• Anterior disarticulation during mandibular protrusive movements

• A nonbruxing patient

• Cost considerations

Materials required for the chairside FRCprosthesis procedure are as follows:

• Diagnostic casts

• Denture or natural tooth

• Intraoral putty occlusal-incisal pontic index

• Phosphoric acid gel etchant


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• Fourth-generation (multiple bottle) or fifthgeneration (single bottle) enamel-dentin bonding

system

• Visible light—curing flowable particulate composite

• Unidirectional pre-impregnated FRC

• Finishing and polishing burs and points

Chairside Fixed Partial Denture:

Initial Visit

• During the initial visit, a shade is selected for the denture tooth, and an alginate impression

of the arch in which the FPD will be placed is taken to create a diagnostic cast.2

• This diagnostic cast is used for selecting and modifying the denture tooth pontic.

Denture Tooth Modification

• A denture tooth of appropriate shade that best fits the shape of the edentulous space and

that matches the anatomic shape of the adjacent teeth is selected. It is modified so as to

lightly contact the proximal surfaces of the abutment teeth and to conform to the ridge of

the edentulous space.

• The denture tooth is then tacked to the cast in an optimal position and a line is inscribed on

its occlusal/lingual surface to indicate where the slots are to be placed in the abutment teeth

at the time of insertion.

• The adjusted denture tooth is modified as follows (1) Proximal Class III preparations are

placed on the mesial and distal facial surfaces.

• These will be used to tack the denture tooth interproximally to the abutment teeth when

first positioned in the mouth. (2) An occlusal/lingual groove, at least 2 mm wide and 2 mm

deep, is prepared, with the base undercut following the occlusal/lingual line drawn earlier.

This groove will receive the FRC.


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Alternative Technique Using Extracted Tooth

• If the natural tooth is unsalvagable and must be extracted, it can be used as the pontic.

• The length of the tooth is determined by measuring from the extraction site to the incisal

edge of the adjacent teeth; the root is then cut from the tooth crown at this determined

length.

• The root canal opening at the apical end is restored by preparing the root canal with a 330

bur to a depth of 1.5 mm. The preparation is restored with particulate composite using an

adhesive technique.The technique for placing the natural tooth crown is similar to that for

a denture tooth.2

Fabrication of an Intraoral, Occlusal-Incisal Pontic Index

• The denture tooth is positioned on the diagnostic cast and a positioning index is fabricated

to aid in the accurate alignment of the denture tooth pontic in the mouth.

• Fabricated from vinyl siloxane putty, the positioning index encompasses the occlusal-

incisal portion of the pontic and the adjacent abutment teeth and fills the occlusal/lingual

groove for the FRC.

• The gingival extension should not block facial access to the Class III proximal retentive

forms of the pontic.2

Chairside Insertion Technique

• The abutment teeth are anesthetized; the denture tooth is tried in to verify fit, shade, and

contour; and a rubber dam is placed.

• Grooves are prepared in the abutment teeth to align with the groove in the denture tooth

these are to be at least 2 mm wide and2 mm deep so as to duplicate the groove in the pontic.

• The occlusal/lingual groove in the denture tooth pontic is sandblasted with 50 pm

aluminum oxide.

• The occlusal/lingual grooves and the interproximal areas of the abutment teeth adjacent to

the edentulous space are etched and treated with a dentin bonding agent.

• The denture tooth is placed in the putty index and positioned in the mouth.2

• A flowable composite is placed and light cured into the Class III interproximal

preparations and onto the proximal surfaces of the abutment teeth.


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• This will tack the pontic in place and allow for the removal of the putty index with-out

dislodging or moving the denture tooth.

• A small amount of high viscosity flowable particulate composite resin is syringed into the

occlusal/lingual grooves, and the proper length of FRC is added into the particulate

composite–based groove.

• Three or more pieces of FRC should be placed and condensed into the groove,below the

occlusal/lingual surface of the abutment teeth or pontic, and then light cured.

• A less viscous flowable particulate composite resin is used to completely fill the remaining

portion of the groove and light cured.

• The rubber dam is removed and occlusal adjustments are made using a high-speed

handpiece with a composite finishing bur.2

Patient presenting with

incisor and peg- right lateral

incisor

Facial view of modified

denture tooth on maxillary

cast.

Lingual view of modified

missing left lateral denture

tooth on maxillary cast.

Proximal view of the

lingualFRC slot prepared on

the modified denture tooth

Intraoral incisalpontic positioning

index with denture tooth on the

maxillary cast. Note that the index

allowsaccess to the interproximal

surfaces ofthe denture tooth and

abutments

Cast with lingual slot

preparations.Slots must be at least

2 mm wide,2mm long, and 2 mm

deep to receive atleast 3 to 4 strips

of FRC material.


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(Source: Martin A. Freilich, Jonathan C.Meiers, Jacqueline P.Duncan, A.JonGoldberg. Fiber

Reinforced Composites In Clinical Dentistry.U.S.A:Quintessence Publishing Co,Inc;2000.)

Rubber dam isolation withthe

lingual slots prepared on the

centralincisor and the canine.

Intraoral incisalpontic positioning

index in place, aligning the denture

tooth pontic in the correct position

Particulate composite resin has

been added interproximally to tack

the ponticprior to removal of the

index. This willhold the pontic for

the placement of the

FRC.

Lingual view of the tacked

pontic, ready for FRC

placement. Notethe alignment

of the pontic groove withthe

slots on the canine and the

centralincisor.

Facial view of the finished chairside

FRC FPD and recontouredpegshaped

right lateral incisor.

Lingual view of the completed

chairside FRC fixed prosthesis. The

lingual contour has not been altered by

the FRC placement.


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SURGICAL APPLICATIONS FOR FIBER REINFORCED COMPOSITES:

• FRC in combination of bioactive modifiers like bioactive glass eliminates several

shortcomings of bulk material made implants of metals, ceramics and polymers. FRC

materials are durable and tough and have proven their suitability to surgical applications

of implantology.

• Particles of bioactive glass (BG) have been added to the surface or inner space of FRC

implants to improve osteoconductivity and osteoinductivity of the FRC material.

• The need for skull reconstructions is increasing mainly due to an increase in decompressive

craniectomies, a life-saving maneuver to relieve intracranial pressure resulting from

swelling of the brain due to e.g. trauma or cerebrovascular accidents. Radiation therapy

can also be given in the presence of FRC implant.

• The most commonly used fibers in medical FRC are made of glass of specific composition

but carbon/graphite fibers have also been tested as spinal fusion cages.8

• Surgically used glass fibers are referred as S glass and they are basically free of leaching

ions in physiologically moist environment like in living tissues with presence of

extracellular liquid.

• Use of carbon/ graphite fibers has been limited due to risk of release of micro and

nanometer scale carbon wear debris to tissues.

• Glass fibers of diameter micrometers are used in implants as continuous fibers which have

been woven to textile form before impregnating and coupling with resin, and this method

inhibits the release of wear debris.

• In the presently used designs of FRC implants, both woven textile form of fibers and

unidirectional continuous fibers are used in the implant construction.

• The role of continuous unidirectional fibers is to connect the outer and inner surface

laminates together for providing high strength to the implant.

• Special features of the FRC cranial implant construction are mesh-like surface laminates

and presence of free space between the outer and inner laminates, which is loaded with

particles of bioactive glass.


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• Long-term durability of the cranioplasty implant is important because according to the

present best knowledge, the cranial defects need years of time to be closed by new forming

bone even the presence of osteoinductive implant materials.

• This is the reason why any of the biodegradable polymers or composites cannot be used

for repairs of large bone defects in the cranium.8

• Biodegradable polymer based materials degrade and loose the mechanical strength too fast

in relation to the bone regeneration.

• With regard to degradable metal alloys of magnesium, there are problems in tissue healing

due to release of hydrogen gas during degradation process.

• Thermoset copolymer and the silanized glass fibers form a durable composite for

fabrication of patient specific and standard shaped implants.

• Biocompatibility of FRC implants is the biocompatibility of its components.

• Presence of BG on the implant surface or inside the implant enhance cell maturation of

differentiated bone forming cells. In many of the FRC implant studies, there have been BG

(S53P4) particles in the FRC implant.

• BGs are synthetic dissolving biocompatible osteoconductive- osteoinductive bone

substitutes. Some compositions (S53P4) of BGs have clinically been used because of

antibacterial and angiogenesis-promoting properties.

• Antimicrobial efficiency has been shown for more than 20 microbe species, including

Staphylococcus aureus and Staphylococcus epidermis, which are the most common

pathogens in periprosthetic infections.

• Clinical studies with cranial FRC-BG implants have been for improving osteogenesis,

angiogenesis and antimicrobial properties and long term protection of brain tissues.

• In the biological environment ions of calcium and phosphorus are released from the BG

and they biomineralize on the material surface, like the surface of glass FRC-BG implant.8

• For cells, at the early stage of osteogenesis, released ions from the BG and slightly

increased pH due to ion exchange reactions are inducing differentiation of mesenchymal

stem cells to cell lines for bone formation.

• This, in conjunction with biomineralization promotes bone growth. A series of reactions

starting at the glass surface followed by a series of biological reactions are occurring with

regard to osseointegration, i.e. bonding between the BG of the implant and bone tissue.


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• The different reaction steps taking place at the glass surface depend not only on the glass

composition but also on the surface topography, surface area of glass, and interstistial fluid

flow in the microenvironment around the glass surfaces.

• In the subsequent steps, calcium and phosphate from the solution, and migrating from the

bulk glass, form first amorphous hydroxyapatite and then crystallize at carbonate

substituted hydroxyapatite layer (HA) at the glass surface.

• This HA layer is compatible with the biological apatite and provides an interfacial bonding

between the material and tissue.

• The present design of FRC-BG cranial implant was approved for clinical use as patient-

specific implant and standard shaped implant in Europe in 2014.

FUTURE ASPECTS FOR THE RESEARCH OF FRCS:

➢ Use of FRCs in dentistry and medicine has now taken the first steps and the use is

increasing rapidly.

➢ New applications are tested due to versatile properties of FRC in terms of biomechanics,

possibility to add biologically active compounds to the medical device structure and into

the polymer matrix.8

➢ The limitations of biodegradable implants and stem cell based tissue engineering

approaches in cranial bone repair can be overcome by using glass FRC-BG implants. New

applications for FRC will be found from orthopaedic and trauma surgery and spine surgery

and in more specific dental fields including dental implantology.

NEW FEATURES AND FUTURE APPLICATIONS

➢ Future research on FRCs needs to focus on many aspects such as optimization of the design

of the frameworks in FRC devices, incorporation of bioactive minerals into the reinforced

resin composites, and the change to fiber binding matrix from resin base to inorganic type.

➢ Another improvement is related to nanotechnology, with the production of functional

structures in the range of 0.1-100 nm by various physical or chemical methods. Dental

nanocomposites provided a cosmetically acceptable result with excellent mechanical

properties.


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➢ The addition of nanofillers particles to resin-based dental materials is the main point

involved with this new trend. The utilization of continuous and discontinuous nanofillers

has been proposed in conjunction with FRCs.

➢ FRC utilization has been proposed also in combination with Computer-Aided-

Design/Computer-Aided-Machining (CAD/CAM) technologies.

➢ The interaction between the two technologies seems to be promising based on limited

information.

➢ One other field where FRCs are starting to be utilized is implantology. Implant

applications could benefit from certain biomechanical properties of FRCs, and the

possibility of incorporating additional bioactive components into the implant structure

may open new research fields.7

➢ FRCs have been suggested for tissue engineering for orthopaedic scaffolds. As

biocompatibility results are promising, FRC biomaterials developed may constitute an

optimized alternative to the other materials used for the reconstruction of craniofacial bone

defects.

➢ The research options with FRC materials are open and future reports about the topic are

expected to widen FRC utilization in both dental and medical fields.7


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Fiber Reinforced Composites in Pediatric Dentistry

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